# 6.4 Solve simple interest applications  (Page 2/8)

 Page 3 / 8

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

$11,450 In $5$ years, Gloria's bank account earned $\text{2,400}$ interest at $\text{5%.}$ How much had she deposited in the account?$9,600

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

## Solution

We are asked to find the interest, $I.$

Organize the given information.

$\begin{array}{ccc}\hfill I& =& ?\hfill \\ \hfill P& =& \text{900}\hfill \\ \hfill r& =& \text{2.1%}\hfill \\ \hfill t& =& \text{10 months}\hfill \end{array}$

 Write the formula. $I=Prt$ Substitute the given information, converting 10 months to $\frac{10}{12}$ of a year. $I=900\left(0.021\right)\left(\frac{10}{12}\right)$ 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. Adriana invested $\text{4,500}$ for $8$ months in an account that paid $\text{1.9%}$ interest. How much interest did she earn?$57.00

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

$143.50 ## Access additional online resources ## Key concepts • The formula $I=Prt$ 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 $I=Prt$ 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) $\text{1200}$ $\text{3%}$ $5$$180

Interest Principal Rate Time (years)
$\text{1500}$ $\text{2%}$ $\text{4}$

Interest Principal Rate Time (years)
$4410$ $\text{4.5%}$ $\text{7}$

$14,000 Interest Principal Rate Time (years) $2212$ $\text{3.2%}$ $\text{6}$ Interest Principal Rate Time (years) $577.08$ $\text{4580}$ $\text{2}$ 6.3% Interest Principal Rate Time (years) $528.12$ $\text{3260}$ $\text{3}$ In the following exercises, solve the problem using the simple interest formula. Find the simple interest earned after $5$ years on $\text{600}$ at an interest rate of $\text{3%.}$$90

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

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

$579.96 Find the simple interest earned after $3$ years on $\text{6,510}$ at an interest rate of $\text{2.85%}.$ Find the simple interest earned after $8$ years on $\text{15,500}$ at an interest rate of $\text{11.425%}.$$14,167

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

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

$3,280 Find the principal invested if $\text{177}$ interest was earned in $2$ years at an interest rate of $\text{3%}.$ Find the principal invested if $\text{70.95}$ interest was earned in $3$ years at an interest rate of $\text{2.75%.}$$860

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

#### Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Jeannette has $5 and$10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
What is the expressiin for seven less than four times the number of nickels
How do i figure this problem out.
how do you translate this in Algebraic Expressions
why surface tension is zero at critical temperature
Shanjida
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
s.
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?    By      