What is $C.I.$ (In $Rs.$) on $Rs. 7500$ for $4$ years if the rate of interest is $10 \%$ p.a. for the first $2$ year and $20 \%$ $p.a.$ for the next $2$ year?

The difference between the $S.I.$ and $C.I.$ obtained on principal amount at $5$ $p.c.p.a.$ after $2$ years is $Rs. 35 .$ What is principal amount (In $Rs.$).

What would be the compound interest (In ₹) accrued on an amount of ₹ $7,400$ @ $13.5$ $p.c.p.a.$ at the end of two years? (rounded off to two digits after decimal)

At what rate per cent compound interest does a sum of money become $16$ times in $4$ years?

A man gave $50 \%$ of his savings of ₹ $84,100$ to his wife and divided the remaining sum among his two sons $A$ and $B$ of $15$ and $13$ years of age respectively. He divided it in such a way that each of his sons, when they attain the age of $18$ years, would receive the same amount at $5 \%$ compound interest per annum. The share of $B$ was (In ₹)

A certain sum of money invested at compound interest becomes $1.44$ times of itself in $2$ years. If twice this sum were lent at simple interest, in how many years would it double itself?