A couple will retire in 40 years, they plan to spend about $40,000 a year when they retire, which should last about 20 years. They believe they can earn 6% interest p.a. on retirement savings.

a/ How much money will the couple need in their account when they retire so that they can spend $35,000 a year for 20 years?

b/ If they make quarterly payments into a saving plan, how much will they need to save each 3 months? Assume the first payment comes in 3 months.

c/ If the couple realizes that in 20 years from now they will need to spend $30,000 on their childs college education, how much they will need to save each 3 months so that they can still have the same retirement plan?

Please write down the complete formula