An investment yields an interest payment of $240 each month. If the simple annual interest rate is 9%, what is the amount of the investment?
Choose the correct choice.
A) $ 28,300
B) $ 30,400
C) $ 31,300
D) $ 32,500
E) $ 32,000

Rationale: "let the principal amount = p simple annual interest = 9 % simple monthly interest = ( 9 / 12 ) = ( 3 / 4 ) % ( 3 / 4 ) * ( p / 100 ) = 240 = > p = ( 240 * 4 * 10 ^ 2 ) / 3 = 80 * 4 * 10 ^ 2 = 320 * 10 ^ 2 = 32000 answer e"
Answer: E