Question

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

A) 3%
B) 3.5%
C) 4%
D) 4.5%

Answer 1

Answer: A) 3%

Is the simple interest rate after 9 years

Explanation:

Formula: Simple Interest: ⇒ $P*i%*n

P = Principal = $300

i = Simple interest rate: ?

n = period of time in years = 9 years

Earned Interes (simple interest sfter 9 years) = $81

Therefore:

$300*i%*9 = $81

i% = $81/($300*9) = $9/$300 = $3/$100 =0.03 = 3%

Answer 2

A) 3%

Explanation:

I = P(RT)

I = interest

P = principle

r= rate

t = time

81 = 300 r * 9

81 = 2700*r

divide by 2700

81/2700 = r

.03 =r

multiply by 100 to get the percent

3 =r