please explain in detail. if possible, please have it in excel format. thank you

29.5. Calculate the price of an option that caps the 3 -month rate, observed in 15 months for the 15-18 month period, at 13\% (quoted with quarterly compounding) on a principal amount of $1,000. The forward interest rate for the period in question is 12% per annum (quoted with quarterly compounding), the 18-month risk-free interest rate (continuously compounded) is 11.5% per annum, and the volatilit) of the forward rate is 12% per annum