At what rate percent per annum will the simple interest on a sum of money be 2/5 of the amount in 10 years?
Answers.
A) 4 %  B) 5 %  C) 6 %  D) 7 %  E) 8 %
Sol.   Let sum = x. Then, S.I. = 2x/5, Time = 10 years.   ∴ Rate = [100 * 2x / x*5*10]% = 4%.   4 %nswer 4 %
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At what rate percent per annum will the simple interest on a sum of money be 2/5 of the amount in 10 years?