How to solve these questions using excel?

1. You are thinking about buying a savings bond. The bond costs $50 today and will mature in 10 years with a value of $100. What annual interest rate will the bond earn?
2. You intend to endow a scholarship that pays $5000 every 6 months, starting 6 months from now on forever. If the appropriate discount rate is 2% per 6-month period, how much money will you have to donate today to endow the scholarship?
3. You have an investment account that started with $1000 10 years ago and which now has grown to $5000. What annual rate of return have you earned (you have made no additional contributions to the account)? If the savings bond earns 15% per year from now on, what will the account's value be 10 years from now?