The least amount is paid back in a 42-month loan with a 7% annual simple interest rate.
The term simple interest refers to a type of interest that is paid only on the principal and not on the interest. We have to note that the time and the interest rate all contribute to increasing the amount of money to be paid back.
In the first case, the amount to be paid back is;
A = $8,000 + ($8,000 * 9 * 3/100)
= $10160
In the second case;
A = $8,000 + ( $8,000 * 7 * 3.5/100)
A =$ 9960
In the third case;
A = $8,000 + ($8,000 * 8 *4/100)
A = $10560
In the fourth case;
A = $8,000 + ($8,000 * 6 * 4.5/100)
A = $10160
Hence, the least amount is paid back in a 42-month loan with a 7% annual simple interest rate.
Learn more about simple interest: https://brainly.com/question/26437826?
