Find the compound interest on $20000 in 2years at 4% per annum, the interest being compounded half-yearly? Pick one
A) $ 645.56	B) $ 1648.64	C) $ 954.26	D) $ 745.69	E) $ 1020.45

Rationale: "principle = $ 20000 rate = 2 % half yearly = 4 half years amount = 20000 * ( 1 + 2 / 100 ) ^ 4 = 20000 * 51 / 50 * 51 / 50 * 51 / 50 * 51 / 50 = $ 21648.64 c . i . = 21648.64 - 20000 = $ 1648.64 answer is b"
Answer: B