Question

A savings account earns 8.4% (APR) interest calculated monthly, paid into the account at the end of 6 months. Cooper deposits $200 into the account at the beginning of the first month. At the end of each month, he deposits an additional $100 into the account. How much interest will Cooper have earned after 6 months?

Answer: $18.90

Answer 1

The answer is $18.90, but you already solved it. 

Answer 2

$ 18.90

Step-by-step explanation:

Interest = 8.4 %

The principal = $ 200

The time = 6 months

Interest =
`(principal * rate * time)/(100)`

or A = P (1 + rt)

= 200 (1 + 0.0864*0.5)

= $ 208.64

We do the same with $ 100

this gives: $ 104.32

Adding the amounts gives: $ 208.64 + $ 104.32

= $ 312.96

$ 312.96 - $ 280 = $ 18.90