NEED HELP FAST WILL FAN AND GIVE MEDAL

Jacob invested $300 in a savings account and earned $81 in interest at the end of 9 years.

What was the interest rate?

A.
3%

B.
3.5%

C.
4%

D.
4.5%

Question

NEED HELP FAST WILL FAN AND GIVE MEDAL 

Jacob invested $300 in a savings account and earned $81 in interest at the end of 9 years. 

What was the interest rate?
 
 A.
3%
 
 B.
3.5%
 
 C.
4%
 
 D.
4.5%

whpalmer4 · Answer

As there's no mention of compounding, this must be simple interest.  To calculate the interest earned, use 

I = PV * i * n

where I is the interest earned, PV is the principal or present value, i is the interest rate, expressed as a decimal, and n is the number of years.

You know everything except i, so rearrange the equation to solve for i, and then plug in the values.