If a principal is invested at an annual interest rate  compounded times a year, then the balance in the account after years is given by

.

If a principal is invested at an annual interest rate compounded continuously, then the balance in the account after years is given by

.

Find Eric and Sonja thinks are correct or not.

Eric and Sonja are determining the worth of a  investment after years in a savings account earning interest compounded monthly.

Find if the  interest is compounded monthly.

Here , and years.

Since interest compounded monthly .

The amount in the account interest is compounded  monthly is .

Find if the  interest is compounded continuously. 

Here , and years.

The amount in the account interest is compounded continuously is .

Sonja thinks that amount is and the actual amount is also , so finally we conclude that Sonja thinks correct .

Sonja thinks correct amount.