Marla earned $400 interest over 2 years on a $4,000 investment. Jovita earned $960 interest over 4 years on her $6000 investment. Who had the higher rate of interest? Explain.

To determine who had the higher rate of interest, we need to compare the interest rates earned by Marla and Jovita. The interest rate can be calculated by dividing the interest earned by the initial investment amount and then multiplying by 100 to express it as a percentage.

First, let's calculate the interest rate for Marla:
Interest rate for Marla = (Interest earned by Marla / Initial investment by Marla) * 100

Marla earned $400 interest on a $4,000 investment over 2 years:
Interest rate for Marla = (400 / 4000) * 100
Interest rate for Marla = 0.1 * 100
Interest rate for Marla = 10%

Now let's calculate the interest rate for Jovita:
Interest rate for Jovita = (Interest earned by Jovita / Initial investment by Jovita) * 100

Jovita earned $960 interest on a $6,000 investment over 4 years:
Interest rate for Jovita = (960 / 6000) * 100
Interest rate for Jovita = 0.16 * 100
Interest rate for Jovita = 16%

Comparing the interest rates, we see that Jovita had a higher rate of interest (16%) compared to Marla (10%). Therefore, Jovita had a higher rate of interest on her investment.