Jeff invests an amount at 4% interest compounded annually. after 3 years, he has $1687.30. what was the original amount jeff invested? $1500 $1200 $1450 $750

In order to determine the principal amount, remember that $1,687.30 is the principal amount plus all interest accumulated over 3 years. 
:
To find the effect of 4% annual interest over 3 years, take 1.04 and raise it to the third power:
1.04³ = 1.125

Divide the final amount, 1687.30 by 1.125 to find the principal amount:
1687.30 ÷ 1.125 = ~1500
Answer is A.