Find the final amount to which an initial deposit of $100$ accumulates over $25$ years at the

following rates of interest:

a$)$ An effective rate of interest corresponding to a nominal rate of discount of $5\%$ pa

convertible quarterly.

b$)6\%$ pa convertible three times per year for the first $15$ years, and thereafter $4\%$ pa

convertible every second year $($or "every other year"$).$

c$)$ An annual effective rate of interest at which a sum of money deposited would triple

in $22$ years.