To solve this problem, we will use the following formula

where r is the interest rate, P is the principal, n is the number of times interest is compounded per unit of t and t is the time. In here where are compounding monthly a rate of 4%. So, r=4% and n=12 since we want to understand how the rate behaves yearly. Since we want to find the final amount after 8 years, we take t=8. So we have

So Kinsley would have 688.20 after 8 years