i am struggling with this question can someone help me

Exercice 3: A small-scale businessman deposits money at the beginning of each year into his savings account, depending on the level of the business' returns. He deposits $1000 in the first year, $3000 in the second year, $5000 in the third and $7000 in the fourth year and annual interest rate of 7%. What is the closest value of the accumulated money in the savings account at the beginning of year 4