A present value of a machine is $800. Its value depletion rate is 10% per annum then find the machine value after 2 years?	Choose the correct choice from the following answers.
A) $ 900 B) $ 810 C) $ 915 D) $ 715 E) $ 648

Rationale: "p = $ 800 r = 10 % t = 2 years machine value after 2 years = p [ ( 1 - r / 100 ) ^ t ] = 800 * 9 / 10 * 9 / 10 = $ 648 answer is e"
Answer: E