Solution
Given that
The Parker's are saving up to go for a family vacation in 3 years
Number of year, n, is 3 years.
They invested $3100 into an account
Principal, P, is $3100
Annual interest rate of 1.36% compounded monthly
a) To find the amount, A, the Parker's account after 3 years, the formula is

Where

Substitute the variables into the formula above

Hence, the amount in the Parker's account after 3 years is $3,229.02 (nearest cent)
b) To find the interest, I, earned on the Parker's investment, the formula is

Where

Substitute the values into the formula to find the interest above

Hence, the interest, I, earned on the Parker's investment is $129.02 (nearest cent)