Two friends Amelia and Bill, each set themselves a target of saving $20000. They each have $9000 to invest. Amelia invests her $9000 in an account that offers an interest rate of 7% per annum compounded annually. Find the value of Amelia's investment after 5 years to the nearest hundred dollars.

1b. [2 marks] Determine the number of years required for Amelia's investment to reach the target.

1c. [3 marks] Bill invests his $9000 in an account that offers an interest rate of r% per annum compounded monthly, where r is set to two decimal places. Find the minimum value of r needed for Bill to reach the target after 10 years.