Question

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

# 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

Solution