I want to accumulate $20,000 by the end of 20 years. I make quarterly equal deposits at the end of each quarter into a saving account that pays r (4) = 4%.

a) Find the size of these deposits.

b) Assume that after 10 years, the bank changes the rate to r (4) = 8%. Find the size of the quarterly equal deposits now required if the $20,000 goal is to be met