Calculate:

a) the present value of the payments using the given periodic interest rate.

b) the future value of the payments at the time of the last payment

1.$300 in 1 months, $400 in 2 months, $500 in 3 months; 1.5% per month.

2.$100 in 3 months, $200 in 4 months, $100 in 5 months; 1% per month.

3.$50 in 6 months, $100 in 8 months, $300 in 10 months; 2% per month.

4.$200 in 4 months, $300 in 6 months, $500 in 11 months; 1.5% per month.