1 MateriTerbuka Simple Interest
Simple InterestInterest
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Chap
ter
6
II
(2)
Simple InterestInterest
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6 - 2
Calculate
Learning
Objectives
Learning
Objectives
After completing this chapter, you will be able to:
…
i
nterest
,
m
aturity
v
alue
,
f
uture
v
alue
, and
p
resent
v
alue
in a
simple interest
environment
…
details of the amount
and
timing of payments in a time
diagram
…
the
equivalent value
on any date
of a
single
payment
or a
stream of payments,
and
Present
LO-1
LO-1
LO-2
(3)
Simple InterestInterest
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Borrower
Example:
Example:
Loan
Loan
Lender
Parties
Parties
Lends the
Lends the
Principal
Principal
Borrower
OWES (Debt)
to Lender
Borrower
OWES (Debt)
to
Lender
LO-1
(4)
Simple InterestInterest
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Borrower
Lender
Earns
(Income)
from Borrower
i.e.
Interest
on
the Principal
Earns
(Income)
from
Borrower
i.e.
Interest
on
the Principal
Borrower
pays
Interest
to
Lender
Borrower
pays
Interest
to
Lender
Rate
of
Interest:
Simple
Interest
…
Calculated
on an ANNUAL or
per annum
(pa) basis
Simple Interest
…
Calculated
on an ANNUAL or
per annum
(pa) basis
(5)
Simple InterestInterest
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Examples
Examples
Invest $1000
at
10%
simple interest
for
one year.
Interest earned is
?
Principal
X
Interest Rate
$1000
*
10%
=
$100
Invest $1000
at
10%
simple interest
for
six months.
Interest earned is
?
Principal
X
Interest Rate
$1000
*
10%
/
2
=
$50
=
(6)
Simple InterestInterest
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Invest $1000
at
10%
simple interest
for
three months
Interest earned is
?
Principal
X
Interest Rate
=
$1000
X
10%
$25
Invest $1000
at
10%
simple interest
for
one month.
Interest earned is
?
Principal
X
Interest Rate
=
$1000
X
10%
/
12
=
$8.33
/
4
=
(7)
Simple InterestInterest
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Up to this point we have taken months to
represent 1/12
thof a year,
i.e. each month is treated
as having the same number of days!
Would it not be more accurate to
calculate the interest due or payable
based on the actual
number of days in
(8)
Simple InterestInterest
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Yes, it would!
In fact, interest continues
to
accumulate
as each day passes!
Invest $1000
at
10%
simple interest
for
30 days!
Interest earned is
?
Example
Example
Principal
x
Interest Rate
=
$1000
*
10%
*
30
Year = 365 days or 366 in a Leap Year
Year
=
365 days
or
366
in a Leap Year
$8.22
=
(9)
Simple InterestInterest
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t
r
P
I
“What is the formula that can
be used to calculate SI?”
Principal
Interest Rate
Time
Four Elements
Four Elements
are involved …
are involved …
Interest
Formula
Formula
Principal
Amount
(loan or
investment)
Principal
Amount
(loan or
investment)
Annual Rate
of SI
Annual Rate
of SI
Amount
(paid or
received)
Amount
(paid or
received)
Time period
…expressed
as a fraction
or a multiple
of a year
Time period
…expressed
as a fraction
or a multiple
of a year
(10)
Simple InterestInterest
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Calculate the
Interest
earned
on
$5000
invested
at 4%
for
7 months.
Formula
Formula
I =
P
r
t
I =
P *
r *
t
$5000
*
.04
*
7 /12
(11)
Simple InterestInterest
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“I may need to invest or
need a loan for a number
of days rather than a
complete
month.”
“How do I calculate the
time
between the
starting date
and the
(12)
Simple InterestInterest
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Add up
the days according to the
days covered by the specific months.
Include
either
the
FIRST
date
or the
LAST
date when doing
this calculation!
Inc
lude
either
the
FIRST
date
or the
LAST
date when doing
this calculation!
Use
a
Number of Days
TABLE
Use
the
TI BAII Plus
calculator
!
There are
three methods
that can be used to
calculate the number of days:
(13)
Simple InterestInterest
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Method 1.
Method 1.
What is
the
interest earned
on
$5000
invested
from
O
ct. 11
thto
Dec.
29
that
4.5%
?
Calculating the
Number of Days
Oct
11
thto end of month =
20
Days
Nov
Total month =
30
Dec
From 1
of month =
stto 29
th29
79
79
(14)
Simple InterestInterest
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Jan
Mar
May
July
Feb
Apr
Jun
Spaces
are
ALL 30 days
except for
February
which can be either
28
or
29 days in a Leap
year!
Aug
Oct
Dec
Nov
Sept
The “
Hand
Calculator!”
The “
Hand
Calculator!”
(15)
Simple InterestInterest
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Thirty days
has
September
,
April
,
June
and
November
.
All the rest
have
31
,
but
February
with just
28 days clear
(16)
Simple InterestInterest
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6 - 16 Day of
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecThe Serial Number of Each Day of the Year
T
ABLE6.2
1 32 60 91 121 152 182 213 244 274 305 335 2 33 61 92 122 153 183 214 245 275 306 336 3 34 62 93 123 154 184 215 246 276 307 337 4 35 63 94 124 155 185 216 247 277 308 338 5 36 64 95 125 156 186 217 248 278 309 339 6 37 65 96 126 157 187 218 249 279 310 340 7 38 66 97 127 158 188 219 250 280 311 341 8 39 67 98 128 159 189 220 251 281 312 342 9 40 68 99 129 160 190 221 252 282 313 343 10 41 69 100 130 161 191 222 253 283 314 344 11 42 70 101 131 162 192 223 254 284 315 345 12 43 71 102 132 163 193 224 255 285 316 346 13 44 72 103 133 164 194 225 256 286 317 347 14 45 73 104 134 165 195 226 257 287 318 348 15 46 74 105 135 166 196 227 258 288 319 349 16 47 75 106 136 167 197 228 259 289 320 350 17 48 76 107 137 168 198 229 260 290 321 351 18 49 77 108 138 169 199 230 261 291 322 352 19 50 78 109 139 170 200 231 262 292 323 353 20 51 79 110 140 171 201 232 263 293 324 354 21 52 80 111 141 172 202 233 264 294 325 355 22 53 81 112 142 173 203 234 265 295 326 356 23 82 113 143 174 204 235 266 296 327 357 24 55 83 114 144 175 205 236 267 297 328 358 25 56 84 115 145 176 206 237 268 298 329 359 26 57 85 116 146 177 207 238 269 299 330 360 27 58 86 117 147 178 208 239 270 300 331 361 28 59 87 118 148 179 209 240 271 301 332 362 29 88 119 149 180 210 241 272 302 333 363 30 89 120 150 181 211 242 273 303 334 364 31 90 151 212 243 304 365 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
363
284
Oct 11
Dec 29
= 79 Days
= 79 Days
Method 2.
Method 2.
(17)
Simple InterestInterest
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12.2902
Us
ing
…
i
Texas Instruments
BAII PLUS
Days Between Dates
D
ays
B
etween
D
ates
2nd
CPT
Enter
Method 3.
Method 3.
Example 1.
Example 1.
Calculate…
the
interest
earned
on
$5000
invested
from
Oct. 11
thto
Dec. 29
th,
02
at
4.5%
.
Start
DBD =
79
Date
(18)
Simple InterestInterest
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Formula
Formula
I =
P
r
t
Calculate the
Interest
earned
on
$5000 invested
at
4.5%
for
?
.
79 Days
I =
$5000
*
.045
*
79/365
(19)
Simple InterestInterest
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Method 1.
Method 1.
What is
the
interest earned
on
$5000
invested
from
Nov 30
th, 02
to
Jan
6
th, 03
at
4.5%
?
Nov
30
thto end of month =
0
Days
Dec
Total month =
31
Jan
From 1
of month =
stto 6
th6
37
37
Includes the last date
(20)
Simple InterestInterest
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6 - 20 Day of
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecThe Serial Number of Each Day of the Year
T
ABLE6.2
1 32 60 91 121 152 182 213 244 274 305 335 2 33 61 92 122 153 183 214 245 275 306 336 3 34 62 93 123 154 184 215 246 276 307 337 4 35 63 94 124 155 185 216 247 277 308 338 5 36 64 95 125 156 186 217 248 278 309 339 6 37 65 96 126 157 187 218 249 279 310 340 7 38 66 97 127 158 188 219 250 280 311 341 8 39 67 98 128 159 189 220 251 281 312 342 9 40 68 99 129 160 190 221 252 282 313 343 10 41 69 100 130 161 191 222 253 283 314 344 11 42 70 101 131 162 192 223 254 284 315 345 12 43 71 102 132 163 193 224 255 285 316 346 13 44 72 103 133 164 194 225 256 286 317 347 14 45 73 104 134 165 195 226 257 287 318 348 15 46 74 105 135 166 196 227 258 288 319 349 16 47 75 106 136 167 197 228 259 289 320 350 17 48 76 107 137 168 198 229 260 290 321 351 18 49 77 108 138 169 199 230 261 291 322 352 19 50 78 109 139 170 200 231 262 292 323 353 20 51 79 110 140 171 201 232 263 293 324 354 21 52 80 111 141 172 202 233 264 294 325 355 22 53 81 112 142 173 203 234 265 295 326 356 23 82 113 143 174 204 235 266 296 327 357 24 55 83 114 144 175 205 236 267 297 328 358 25 56 84 115 145 176 206 237 268 298 329 359 26 57 85 116 146 177 207 238 269 299 330 360 27 58 86 117 147 178 208 239 270 300 331 361 28 59 87 118 148 179 209 240 271 301 332 362 29 88 119 149 180 210 241 272 302 333 363 30 89 120 150 181 211 242 273 303 334 364 31 90 151 212 243 304 365 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
54
6
365
334
Jan 6
=
=
37
37
Days
Days
Method 2.
Method 2.
Nov 30
Dec 31
(21)
McGraw-Hill Ryerson©
Simple InterestInterest
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01.0603
Us
ing
…
i
Texas Instruments
BAII PLUS
Days Between Dates
D
ays
B
etween
D
ates
2nd
CPT
Enter
Method 3.
Method 3.
Example 1.
Example 1.
Calculate…
the
interest
earned
on
$5000
invested
from
Nov.
30
th,, 02
to
Jan
6
th. 03
at
4.5%
.
Start
DBD =
37
Date
(22)
Simple InterestInterest
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Formula
Formula
I =
P
r
t
I =
$5000
*
.045
*
37/365
I = $22.81
I = $22.81
Calculate the
Interest
earned
on
$5000 invested
at
4.5%
for
?
.
(23)
Simple InterestInterest
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Method 1.
Method 1.
What is
the
interest earned
on
$5000
invested
from
Oct 11
th, 02
to
Mar
11
th, 03
at
4.0%
?
Oct
11
thto end of month = 20
Days
Total = 61
Total = 59
151
151
Jan & Feb
Mar
To 11
thof month =
11
Nov & Dec
30
31
28
31
Includes the last date
(24)
Simple InterestInterest
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6 - 24 Day of
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecThe Serial Number of Each Day of the Year
T
ABLE6.2
1 32 60 91 121 152 182 213 244 274 305 335 2 33 61 92 122 153 183 214 245 275 306 336 3 34 62 93 123 154 184 215 246 276 307 337 4 35 63 94 124 155 185 216 247 277 308 338 5 36 64 95 125 156 186 217 248 278 309 339 6 37 65 96 126 157 187 218 249 279 310 340 7 38 66 97 127 158 188 219 250 280 311 341 8 39 67 98 128 159 189 220 251 281 312 342 9 40 68 99 129 160 190 221 252 282 313 343 10 41 69 100 130 161 191 222 253 283 314 344 11 42 70 101 131 162 192 223 254 284 315 345 12 43 71 102 132 163 193 224 255 285 316 346 13 44 72 103 133 164 194 225 256 286 317 347 14 45 73 104 134 165 195 226 257 287 318 348 15 46 74 105 135 166 196 227 258 288 319 349 16 47 75 106 136 167 197 228 259 289 320 350 17 48 76 107 137 168 198 229 260 290 321 351 18 49 77 108 138 169 199 230 261 291 322 352 19 50 78 109 139 170 200 231 262 292 323 353 20 51 79 110 140 171 201 232 263 293 324 354 21 52 80 111 141 172 202 233 264 294 325 355 22 53 81 112 142 173 203 234 265 295 326 356 23 82 113 143 174 204 235 266 296 327 357 24 55 83 114 144 175 205 236 267 297 328 358 25 56 84 115 145 176 206 237 268 298 329 359 26 57 85 116 146 177 207 238 269 299 330 360 27 58 86 117 147 178 208 239 270 300 331 361 28 59 87 118 148 179 209 240 271 301 332 362 29 88 119 149 180 210 241 272 302 333 363 30 89 120 150 181 211 242 273 303 334 364 31 90 151 212 243 304 365 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 54
Oct 11
Dec 31
365
284
=
=
81
81
Days
Days
Mar 11
70
=
=
70
70
Days
Days
=
=
151
151
Days
Days
(25)
McGraw-Hill Ryerson©
Simple InterestInterest
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03.1103
Us
ing
…
i
Texas Instruments
BAII PLUS
Days Between Dates
D
ays
B
etween
D
ates
2nd
CPT
Enter
Method 3.
Method 3.
Example 1.
Example 1.
Calculate…
the
interest
earned
on
$5000
invested
from
Oct.
11
th,, 02
to
Mar
11
th. 03
at
4.0%.
Start
DBD =
151
Date
(26)
Simple InterestInterest
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Formula
Formula
I =
P
r
t
I =
$5000
*
.04
*
151/365
I = $82.74
I = $82.74
Calculate the
Interest
earned
on
$5000 invested
at
4.0%
for
?
.
(27)
Simple InterestInterest
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Formula
Formula
I =
P
r
t
We can
‘reorganize’
the formula to also get
each of the following separately:
Principal
Rate
Rate
Time
Time
(28)
Simple InterestInterest
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I
P
r
t
Formula
Formula
I =
P
r
t
To
help
remember this…
we can place the formula into a triangle as follows…
The
Tria
ngle
…another useful
non
-calculator!
Where
variables
are
BESIDE
EACH OTHER
this
means to
MULTIPLY!
Using this
Using this
tool!
tool!
P*r*t
P*
r*
t
I
P
r
t
Where a
variable is
ABOVE
ANOTHER
this means to
(29)
Simple InterestInterest
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If you want to find
P
then
I
/
r
t
If you want to find
r
then
I
/
P
r
then
I
/
P
t
If you want to find
t
Using this
Using this
tool!
tool!
I
P
r
t
(30)
Simple InterestInterest
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What is
a Time
Line?
A
Time Line
is, as the name suggests, a line
that shows the various points of time along
which a loan or investment travels to maturity.
It is used for diagramming problems involving
multiple payments or investments.
Two Benefits
Two Benefits
…Helps organize data
…Helps organize data
…Indicates the steps needed
to implement the solution
…Indicates the steps needed
to implement the solution
Using
a
Time Line
Time Line
(31)
McGraw-Hill Ryerson©
Simple InterestInterest
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Calculate the interest earned at 4% on $5000
invested from Oct. 11
thto March 11
thCalculate the
interest
earned at
4%
on
$5000
invested from
Oct. 11
thto
March 11
thDraw a line for
the entire period
Step 1
Step 1
Oct 11
March 11
$5000
Start
Finish
Enter the key
dates on the line
Step 2
Step 2
Dec 31
Enter the
number of days
between
each date and
add
Step 4
Step 4
81 days
70 days
151 days
Enter the
Investment
Step 3
Step 3
The calculation can now be
restated as follows…
284
365
70
Look up
Using
a
Time Line
Time Line
(32)
Simple InterestInterest
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Calculate the interest earned at 4% on $5000
invested for 151 days.
Calculate the interest earned at
4%
on
$5000
invested for
151 days
.
I
=
5000
*
Using this
Using this
tool!
tool!
I
P
r
t
=
$
82.74
I =
P
r
t
.04
*
151/365
(33)
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You can now use this
You can now use this
tool!
tool!
I
P
r
t
In the next few examples you have to…
(a)
First identify
which variable you are
being asked to solve for, and
In the next few examples you have to…
(a)
First
identify
which variable you are
being asked to solve
for
,
and
(b)
Reorganize the formula
in order to
meet the requirement in (a).
(b)
Reorganize
the formula
in order to
(34)
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Calculating
the
Principal
Principal
Formula
Formula
P=
I
r
t
P =
$
195
.
0525
*(
150
/
365
)
P =
$
195
P =
$9,038.10
.0121575342
$195
interest
is
earned
on a
150 day
GIC
at 5.25%
.
Find the
initial
investment
.
(35)
Simple InterestInterest
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.0525
*
150
/
365
=
/
195
=
$9038.10
$9038.10
1/x
1/x
9038.10
(36)
Simple InterestInterest
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Calculating the
Calculating the
Rate
Rate
What Rate of Interest is
needed to earn $200 on a
$5000 investment invested for
180 days?
What Rate
of Interest
is
needed to
earn
$200
on a
$5000
investment
invested for
180 days?
r
=
Formula
Formula
r
=
I
P
t
/
($5000
*
180/365
)
$200
$200
0.081111
or
8.11%
/2465.75
r
=
(37)
Simple InterestInterest
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5000
*
180
/
365
=
/
200
=
8.11%
8.11%
1/x
1/x
0.08111
/
($5000
*
180/365
)
(38)
Simple InterestInterest
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Calculating the
Calculating the
Time
Time
What is the length of Time
required for $2000 to grow to
$2100 when invested at
5.6%?
What is the length of
Time
required for
$2000
to grow to
$
2
100
when invested at
5.6%?
Formula
Formula
t
=
I
P
r
Step 1
Step 1
Find the amount of Interest
Find the amount of
Interest
$
2
100
P
P
=
$100
More
-
$2000
I
I
(39)
Simple InterestInterest
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What is the length of Time
required for $2000 to grow to
$2100 when invested at 5.6%?
What is the length of
Time
required for
$2000
to grow to
$2100 when invested at 5.6%?
t =
/ ($2000*.056)
/ (
$2000
*
.056
)
t =
$100
$100
/ 112
t =
0.8928 Years
t =
326 days
Step 2
Calculate
Step 2
Calculate
Calculating the
Calculating the
Time
Time
Formula
Formula
t
=
I
P
r
(40)
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100
2000
/
0.056
=
365
=
326 days
326 days
325.89
/ ($2000*.056)
/ (
$2000
*
.056
)
$100
t
=
/
0.8928 Years
(41)
Simple InterestInterest
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(42)
Simple InterestInterest
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Formula
Formula
I =
P
r
t
P
+
I
S
um =
Up to this point we have used two
formulae:
Now, we substitute for
Now, we substitute for
I
I
with
with
P
rt
Step 1
Step 1
P
+
S
um =
Collecting like terms
Collecting like terms
Formula
Future Value
F
uture
V
alue
S
um
=
P
(
1
+
r
t
)
Step 2
Step 2
&
S
um =
P
+
I
We can combine them as follows:
(43)
Simple InterestInterest
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S
um =
P
(1+
r
t
)
I place $17000
in a 150 day
term deposit on
Jan. 6 paying
6.5%.
I place
$17000
in a
150 day
term
deposit
on
Jan. 6 paying
6.5%.
How much will
the bank pay
me on the
maturity date
?
How much will
the bank pay
me on the
maturity date
?
S
=
$
17
454.11
S
=
$
17000
(
1.0267123
)
S
=
$
17000
1+ .065
(
150
)
(44)
McGraw-Hill Ryerson©
Simple InterestInterest
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.065
Date of Maturity
*
150
/
365
=
+
1
=
$17454.11
$
17
454.11
*
17000
S
=
$17000
1+ .065
(
150
)
365
17454.11
(45)
Simple InterestInterest
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Day of
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecThe Serial Number of Each Day of the Year
T
ABLE6.2
1 32 60 91 121 152 182 213 244 274 305 335 2 33 61 92 122 153 183 214 245 275 306 336 3 34 62 93 123 154 184 215 246 276 307 337 4 35 63 94 124 155 185 216 247 277 308 338 5 36 64 95 125 156 186 217 248 278 309 339 6 37 65 96 126 157 187 218 249 279 310 340 7 38 66 97 127 158 188 219 250 280 311 341 1 2 3 4 5 6 7
Determine the
Maturity
Date
Determine the
Maturity
Date
I place $17000 in a 150 day term
deposit on Jan. 6 paying 6.5%
deposit
I place
on Jan. 6 paying
$17000
in a
150 day term
6.5%
pa
pa
.
.
= 6 days
+
150 = 156 days
Find
156
Find
156
The Term Deposit will
mature on June 5
th
.
(46)
Simple InterestInterest
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5,000
8,000
10,000
During the year, I invested the
following funds at a constant 4% p.a.
Feb 14
th$5,000
Mar 17
th$3,000
July 1
st$2,000
What Total amount will I have on December 29
What Total amount will I have on December 29
th
th
?
?
(The second and third amounts were
added to the Feb 14
thamount.)
(47)
Simple InterestInterest
6
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6 - 47
Step
1
Three Steps
are required to solve this problem:
Draw a time line
,
including the dates
and dollar amounts.
Step
2
Determine the time
between each of the
dates
Step
3
Calculate the
interest
amounts
,
and
add
(48)
Simple InterestInterest
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6 - 48
Step
1
Draw a
time
line
Feb 14
March 17
July 1
Dec 29
45
76
182
363
$500
0
$300
0
$200
0
363 – 45 = 318 Days
363 – 76 = 287 Days
Step
2
Determi
ne the
Time
363 – 182 = 181 Days
(49)
McGraw-Hill Ryerson©
Simple InterestInterest
6
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6 - 49
S = $10308.28
Total Amount
S = $
10
308.28
Total Amount
Step
3
Calculat
e the
Interest
amount
s,
and
add
togethe
r
.
Calculat
e the
Interest
amount
s,
and
add
togethe
r
.
Formula
Formula
I =
P
r
t
I
1=
5000
*
.04
*
318/365
$174.25
I
2=
3000
*
.04
*
287/365
I
3=
2000
*
.04
*
182/365
94.36
39.67
$
308.28
$10000 +
$10000 +
$308.2
8
$
308.2
8
(50)
McGraw-Hill Ryerson©
Simple InterestInterest
6
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6 - 50
“During the year I made an
investment that had changes in
the
rate of interest
.
How do I determine the total
interest earned
during the
period under review?”
Every time the interest rate
changes
,
you
must stop
and
make a calculation up to
that point.
(51)
Simple InterestInterest
6
6
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I
invest $1,000
on Feb. 14th at
6%
.
The changes in interest rates to July 4
thare as follows:
Investment
Date
rate
$1,000
Feb 14
th6%
April 20
th6.8%
May 18
th7.1%
(52)
Simple InterestInterest
6
6
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Look up
for Days
… by finding the number of days between
each rate change!
Investment
Date
rate
$1,000
Feb 14
th6%
April 20
th6.8%
May 18
th7.1%
(53)
Simple InterestInterest
6
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6 - 53
= 45
= 110
= 65 Days
= 28 Days
Number
of Days
Number
of Days
Table
reading
Table
reading
Look up
for Days
Feb 14
thApril 20
thMay 18
thJuly 4th
= 47 Days
Interest Earned
Interest Earned
= 138
(54)
Simple InterestInterest
6
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Feb 14
thApril 20
65 Days
thFormula
Formula
I =
P
r
t
I
1=
1000
*
.06
*
65/365
=
$10.68
May 18
th28 Days
I
2=
1000
*
.068
*
28/365
I
3=
1000
*
.071
*
47/365
= 5.22
July 4th
47 Days
= 9.14
$25.04
$25.04
Interest
Earned
Interest
Earned
(55)
Simple InterestInterest
6
6
6
6
(56)
Simple InterestInterest
6
6
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6 - 56
What are we being asked
to provide
?
“How much
must I
invest
…
to grow…”
“How much
must I
invest
…
to grow…”
…this suggests finding the
P
rincipal
How
much
must
I invest
in order for it
to
grow to $5000
within
6 months
(57)
Simple InterestInterest
6
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What data do
we need
?
We need the
appropriate data
to be
able to use the
appropriate formula
…
We need the
appropriate data
to be
able to use the
appropriate formula
…
Formulae
Formulae
I
=
P
r
t
&
S
um =
P
(1+
r
t
)
How
much
must
I invest
in order for it
to
grow to $5000
within 6 months, @ 4.4% simple interest?
How
much
must
I invest
in order for it
to
grow to $5000
(58)
Simple InterestInterest
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r
=
4.4%
t
=
6 months
=
.5
S
um =
$5000
How
much
must
I invest
in order for it
to
grow to $5000
within 6 months, @ 4.4% simple interest?
How
much
must
I invest
in order for it
to
grow to $5000
within
6 months
,
@ 4.4% simple interest
?
What data do
we have
?
(59)
Simple InterestInterest
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As we know the
S
um, the formula now becomes…
How
much
must
I invest
in order for it
to
grow to $5000
within 6 months, @ 4.4% simple interest?
How
much
must
I invest
in order for it
to
grow to $5000
within
6 months
,
@ 4.4% simple interest
?
Formulae
Formulae
I
=
P
r
t
&
S
um =
P
(1+
r
t
)
Using
S
um =
P
(1+
r
t
)
(60)
Simple InterestInterest
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6
6 - 60
P
=
5000
/ 1 +
0.044
(
.5
)
P
P
= $4892.37
=
$4892.37
How
much
must
I invest
in order for it
to
grow to $5000
within 6 months, @ 4.4% simple interest?
How
much
must
I invest
in order for it
to
grow to $5000
within
6 months
,
@ 4.4% simple interest
?
(61)
Simple InterestInterest
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6
6
6 - 61
LO-2
LO-2
Simple InterestInterest
6
6
6
6
(62)
Simple InterestInterest
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6
6
6 - 62
Futur
e
Value
What is the equivalent value on
September 15
of a $2000 payment on July
4, if money is worth 6% pa?
What is the
equivalent value
on
September 15
of a $2000 payment on July
4, if money is worth 6% pa?
Step
1
Step
2
Draw a
Timeline
July 4
September 15
$2000
2000
[1+
.06
(
69/365
)]
=
=
$2022.68
$
2022.68
S
um =
69 Days
(63)
Simple InterestInterest
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6 - 63
Presen
t
Value
What is the equivalent value
on May 18th
of a $2000 payment due on the following
December 15th if money can earn 5.2%?
What is the
equivalent value
on May 18th
of a $2000 payment due on the following
December 15th if money can earn 5.2%?
Step
1
Step
2
Draw a
Timeline
May 18
December 15
$2000
=
2000
/[1+
.052
(
211/365
)]
211 Days
=
=
$1941.63
$
1941.63
(64)
Simple InterestInterest
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6 - 64
Heather owes Mark $3000 payable
on April 27.
If money can
earn 4%,
what
amount should Mark accept in
settlement of the debt:
A)
30 days before
the scheduled
payment?
B)
90 days before
the scheduled
payment?
(65)
Simple InterestInterest
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6 - 65
Step
1
Draw a
Timeline
April 27
P
resent
V
alue
30 days
90 days
$3000
Step
(66)
Simple InterestInterest
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A
A
P
=
3000
/[1+
.04
(
30/365
)]
P
P
=
=
$2990.17
$2990.17
B
B
P
=
3000
/[1+
.04
(
90/365
)]
P
P
=
=
$2970.17
$2970.17
(67)
Simple InterestInterest
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You can prepay $1234 tuition for a course
or delay payment for 3 months and pay
$1432.
If you can
earn 6%
on your money,
(68)
Simple InterestInterest
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Data
$1234 =
P
resent
V
alue =
P
1
$
1432
=
F
uture
V
alue =
S
2
P
2
=
1432
/[1+.
06
(
.25
)]
Tip:
Find the
PV of the
future
payment!
Tip:
Find the
PV of the
future
payment!
P
2
=
$1410.84
Money saved ($176.84) by paying now!
Which
formula
should
you use?
Which
formula
should
you use?
$1234.00
P
P
=
=
Sum/(1+rt)
S
um/(1+
r
t
)
3
months
= 1/4
3
months
= 1/4
(69)
Simple InterestInterest
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This completes Chapter 6
(1)
Heather owes Mark $3000 payable on April 27.
If money can
earn 4%,
what amount should Mark accept insettlement of the debt:
A) 30 days before the scheduled
payment?
(2)
Simple Interest
Simple Interest
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6
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6 - 65
Step 1
Draw a
Timeline
April 27
Present Value
30 days
90 days
$3000
Step
(3)
A
A
P
=
3000
/[1+
.04
(
30/365
)]
P
P
=
=
$2990.17
$2990.17
B
B
P
=
3000
/[1+
.04
(
90/365
)]
(4)
Simple Interest
Simple Interest
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6 - 67
You can prepay $1234 tuition for a course
or delay payment for 3 months and pay $1432.
If you can earn 6% on your money, which option should you choose?
(5)
Data
$
1432
=
F
uture
V
alue =
S
2P
2=
1432
/[1+.
06
(
.25
)]
Tip:
Find the PV of the
future payment!
Tip:
Find the PV of the
future
payment!
P
2=
$1410.84
Which
formula
should
you use?
Which
formula
should
you use?
$1234.00
P
P
=
=
Sum/(1+rt)
Sum/(1+r
t
)
3 months = 1/4 3 months = 1/4
(6)
Simple Interest
Simple Interest
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