detailed answer please. thank you

1. Dr. Villanueva purchased a 4 year bond with annual coupons of 6%. It is priced to earn an effective annual interest rate of 3.5%. Its face amount is equal to its redemption amount of $1,000. Compute its duration. 2. Dr. Yang purchased a 4 year bond had annual coupons of 2%. It is priced to earn an effective annual interest rate of 3.5%. Its face amount is equal to its redemption amount of $1,000. Compute its duration and compare it to the duration of Dr. Villanueva's bond. Explain the difference. 3. Show that the duration of an n period annuity immediate is 1vnaninvn