Solve the following interest problem statements:

a.Find the rate of interest if the amount owed after 8 years is Rs 21000, borrowed amount being Rs 4000.

b.How long does it take for money to triple at 8% p.a compounded semi annually?

c.Find the compound amount and compound interest at the end of 10 years on a sum of Rs 30,000 borrowed at 4% compound monthly.

d.Determine the number of months required for deposit of Rs 21200 to earn Rs 520 interest at 10 %.

e.Determine the rate of return required for a deposit of Rs 15,800 to earn Rs 550 for 8 years p.a compounded quarterly.