A sum of money doubles itself at compound interest in 15 years.in how many years will it become eight times?
34 years
37 years
45 years
47 years
Correct Answer :
C. 45 years
P(1+R/100)15=2P
(1+R/100)15=2P/P=2
LET P(1+R/100)n=8P
(1+R/100)n=8=23={(1+R/100)15}3[USING (I)]
(1+R/100)N=(1+R/100)45
n=45.
Thus, the required time=45 years.