$($b$)$ A person deposits Rs$.10,000,$ Rs$.20,000,$ Rs$.30,000$ and Rs$.40,000$ in his

deposit account in the beginning of first year, second year, third and fourth

year respectively. Determine the account balance at the end of $4^{th}$ year, if the

interest rate is $12\%.$ How your answer would change if$,$ the same amount is

deposited at the end of first year, second year, third year and fourth year

respectively.

OR