investment certificates

1. Greg wants to have $50 000 in five years. He has S20 000 todav to invest. The bank is offering five-year investment certificates that pay interest compounded quarterly. ~V\ nat is the minimum nominal interest rate he would have to receive to reach his goal?
2. Greg wants to have $50 000. He will invest S20 000 today in investment certificates that pay 8% nominal interest, compounded quarterly. How long will it take him to reach his goal?