Question

Marla invested $78,170 in a simple interest account. After 9 years and no additional deposits or withdrawals, the account balance was $150,606.59. Find the interest rate for the account.

Answer 1

Divide150606. 59by78170then take ninth root and subtract 1fromThe answer then multiply the answer by 100

Answer 2

The interest rate for the account is
`10.30\%`

Explanation:

we know that

The simple interest formula is equal to

`A=P(1+rt)`

where

A is the Final Investment Value

P is the Principal amount of money to be invested

r is the rate of interest

t is Number of Time Periods

in this problem we have

`t=9\ years\\ P=\$78,170\\ A=\$150,606.59\\r=?`

substitute in the formula above and solve for r

`150,606.59=78,170(1+9r)`

`9r=(150,606.59/78,170)-1`

`r=0.9267/9=0.1030`

convert to percentage

`0.1030*100=10.30\%`