Find the least number of complete years in which a sum of money put out at $20 \%$ compound interest will be more than double?

Which information given below is sufficient to know the amount if the difference between the $C.I. \& S.I.$ for $2$ years is $18$?

($I$) The rate is same at which an amount of $Rs. 1000$ become $1120$ for $2$ years in $S.I.$

($II$) The principal given is $Rs. 2000$.

In how many years will a sum of ₹ $800$ at $10 \%$ per annum compound interest, compounded semiannually becomes ₹ $926.10$?

At what rate per cent per annum will ₹ $1000$ amount to ₹ $1331$ in $3$ years? The interest is compounded yearly.

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 ₹)

What would be the $C.I.$ obtained on an amount of $12500$ at the rate of $12 \,p.c.p.a.$ after $2$ years (In $Rs.$) ?