Question

You put $400 in an account. The account earns $18 simple interest in 9 months. What is the annual interest rate?

Answer 1

I=PRT
Interest=Principal times Rate time Time
time is in years and rate is in decimal

I=18
P=400
T= 9/12=3/4=0.75
R=?


18=400*R*0.75
18=300*R
divide both sides by 300
0.06=R

rate is 6%