Question

7. A sum of money lent out at C.I. at a certain
rate per annum becomes three times of itself
in 10 years. Find in how many years will the money become twenty seven time of itself at the same rate of interest p.a.​

Answer 1

Hi! Here is the answer to your question. Let the sum of money be Rs P and the rate of interest be r % p.a. Amount at the end of 8 years = Rs 3P Formula for amount= P(1+(r/100))^n where n=time,p=principal and r=rate 3P=P(1+(r/100))^8 3=(1+(r/100)^8 .............1 Let the money becomes 27 times in n years 27P=P(1+(r/100))^n 27=1+(r/100))^n (3)^3=1+(r/100)^n (1+(r/100))^8)^3=1+(r/100))^n from 1 1+(r/100))^24=1+(r/100)^n Comparing bases we get n=24 years

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