### Home > MC2 > Chapter 4 > Lesson 4.2.2 > Problem4-42

4-42.

Latisha wants to get at least a $\text{B}+$ in her history class. To do so, she needs to have an overall average of at least $86\%$. So far, she has taken three tests and has gotten scores of $90\%$, $82\%$, and $81\%$.

1. Use the 5-D Process to help Latisha determine what percent score she needs on the fourth test to get the overall grade that she wants. The fourth test is the last test of the grading period.

Remember, you are trying to find the average. Set up an equation that will help you find the score Latisha needs to get an average of $86\%$.

$\frac{90+82+81+?}{4}=86$

$91\%$

2. The teacher decided to make the last test worth twice as much a regular test. How does this change the score that Latisha needs on the last test to get an overall average of $86\%$? Support your answer with mathematical work. You may choose to use the 5-D Process again.

Since the last test is worth twice as much, it is essentially two scores for the same test.

$\frac{90+82+81+2(?)}{5} = 86$