Question

מו 39. A sum of money doubles itself in yr at compound interest. It will amount to 8 times itself at the same rate of interest in (1) 18 yr (2) 12 yr (3) 16 yr (4) 24 yr

11th - 12th Class

Maths

Solution

153

4.0 (1 ratings)

39. (2) According to the question. [ begin{array}{l} 2 x=xleft(1+frac{r}{100}right)^{4} 2=left(1+frac{r}{100}right)^{4} end{array} ] Again, ( 8 x=xleft(1+frac{r}{100}right)^{n} ) ( 2^{3}=left(1+frac{r}{100}right) ) ( left(1+frac{r}{100}right)^{4 times 3}=left(1+frac{r}{100}right)^{n} ) [: : from Eq. On comparing, ( n=12 ) yr