Chapter 12.3, Problem 3LC

To determine

To find: The minimum grade required in the last test in order to achieve an average of $90$ .

Answer to Problem 3LC

  $94$

Explanation of Solution

Given information:

A student has gotten $87,95,86,\text{ and }88$ grades in his tests. An average of $90$ is required to receive an A for the class.

Calculation:

Let $x$ grade is required in fifth test.

  $\begin{array}{l}\text{So, }\frac{87+95+86+88+x}{5}=90\\ \Rightarrow \frac{356+x}{5}=90\\ \Rightarrow 356+x=450\\ \Rightarrow x=450-356\\ \Rightarrow x=94\end{array}$

Hence, student would need minimum $94$ grades in fifth exam to achieve an A in the class.