<< Chapter < Page Chapter >> Page >

Sean's new car loan statement said he would pay $4,866.25 in interest from an interest rate of 8.5% over 5 years. How much did he borrow to buy his new car?

$11,450

Got questions? Get instant answers now!

In 5 years, Gloria's bank account earned $2,400 interest at 5%. How much had she deposited in the account?

$9,600

Got questions? Get instant answers now!

In the simple interest    formula, the rate of interest is given as an annual rate, the rate for one year. So the units of time must be in years. If the time is given in months, we convert it to years.

Caroline got $900 as graduation gifts and invested it in a 10-month certificate of deposit that earned 2.1% interest. How much interest did this investment earn?

Solution

We are asked to find the interest, I .

Organize the given information.

I = ? P = $900 r = 2.1% t = 10 months

Write the formula. I = P r t
Substitute the given information, converting 10 months to 10 12 of a year. I = $900 ( 0.021 ) ( 10 12 )
Multiply. I = 15.75
Check your answer. Is $15.75 a reasonable amount of interest?
If Caroline had invested the $900 for a full year at 2% interest, the amount of interest would have been $18. Yes, $15.75 is reasonable.
Write a complete sentence that answers the question. The interest earned was $15.75.
Got questions? Get instant answers now!
Got questions? Get instant answers now!

Adriana invested $4,500 for 8 months in an account that paid 1.9% interest. How much interest did she earn?

$57.00

Got questions? Get instant answers now!

Milton invested $2,460 for 20 months in an account that paid 3.5% interest How much interest did he earn?

$143.50

Got questions? Get instant answers now!

Key concepts

  • The formula I = P r t can be used to calculate the amount of interest on an investment. See [link] .
  • By writing an equation based on information provided about simple interest, any value in the equation I = P r t can be found. See [link] .

Practice makes perfect

Use the Simple Interest Formula

In the following exercises, use the simple interest formula to fill in the missing information.

Interest Principal Rate Time (years)
$1200 3% 5

$180

Got questions? Get instant answers now!

Interest Principal Rate Time (years)
$1500 2% 4

Got questions? Get instant answers now!

Interest Principal Rate Time (years)
$4410 4.5% 7

$14,000

Got questions? Get instant answers now!

Interest Principal Rate Time (years)
$2212 3.2% 6

Got questions? Get instant answers now!

Interest Principal Rate Time (years)
$577.08 $4580 2

6.3%

Got questions? Get instant answers now!

Interest Principal Rate Time (years)
$528.12 $3260 3

Got questions? Get instant answers now!

In the following exercises, solve the problem using the simple interest formula.

Find the simple interest earned after 5 years on $600 at an interest rate of 3%.

$90

Got questions? Get instant answers now!

Find the simple interest earned after 4 years on $900 at an interest rate of 6%.

Got questions? Get instant answers now!

Find the simple interest earned after 2 years on $8,950 at an interest rate of 3.24% .

$579.96

Got questions? Get instant answers now!

Find the simple interest earned after 3 years on $6,510 at an interest rate of 2.85% .

Got questions? Get instant answers now!

Find the simple interest earned after 8 years on $15,500 at an interest rate of 11.425% .

$14,167

Got questions? Get instant answers now!

Find the simple interest earned after 6 years on $23,900 at an interest rate of 12.175% .

Got questions? Get instant answers now!

Find the principal invested if $656 interest was earned in 5 years at an interest rate of 4% .

$3,280

Got questions? Get instant answers now!

Find the principal invested if $177 interest was earned in 2 years at an interest rate of 3% .

Got questions? Get instant answers now!

Find the principal invested if $70.95 interest was earned in 3 years at an interest rate of 2.75%.

$860

Got questions? Get instant answers now!

Find the principal invested if $636.84 interest was earned in 6 years at an interest rate of 4.35%.

Got questions? Get instant answers now!

Questions & Answers

what is phylogeny
Odigie Reply
evolutionary history and relationship of an organism or group of organisms
AI-Robot
ok
Deng
what is biology
Hajah Reply
the study of living organisms and their interactions with one another and their environments
AI-Robot
what is biology
Victoria Reply
HOW CAN MAN ORGAN FUNCTION
Alfred Reply
the diagram of the digestive system
Assiatu Reply
allimentary cannel
Ogenrwot
How does twins formed
William Reply
They formed in two ways first when one sperm and one egg are splited by mitosis or two sperm and two eggs join together
Oluwatobi
what is genetics
Josephine Reply
Genetics is the study of heredity
Misack
how does twins formed?
Misack
What is manual
Hassan Reply
discuss biological phenomenon and provide pieces of evidence to show that it was responsible for the formation of eukaryotic organelles
Joseph Reply
what is biology
Yousuf Reply
the study of living organisms and their interactions with one another and their environment.
Wine
discuss the biological phenomenon and provide pieces of evidence to show that it was responsible for the formation of eukaryotic organelles in an essay form
Joseph Reply
what is the blood cells
Shaker Reply
list any five characteristics of the blood cells
Shaker
lack electricity and its more savely than electronic microscope because its naturally by using of light
Abdullahi Reply
advantage of electronic microscope is easily and clearly while disadvantage is dangerous because its electronic. advantage of light microscope is savely and naturally by sun while disadvantage is not easily,means its not sharp and not clear
Abdullahi
cell theory state that every organisms composed of one or more cell,cell is the basic unit of life
Abdullahi
is like gone fail us
DENG
cells is the basic structure and functions of all living things
Ramadan
What is classification
ISCONT Reply
is organisms that are similar into groups called tara
Yamosa
in what situation (s) would be the use of a scanning electron microscope be ideal and why?
Kenna Reply
A scanning electron microscope (SEM) is ideal for situations requiring high-resolution imaging of surfaces. It is commonly used in materials science, biology, and geology to examine the topography and composition of samples at a nanoscale level. SEM is particularly useful for studying fine details,
Hilary
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply
Practice Key Terms 4

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Prealgebra. OpenStax CNX. Jul 15, 2016 Download for free at http://legacy.cnx.org/content/col11756/1.9
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Prealgebra' conversation and receive update notifications?

Ask