Question

To get an A in history, Matthew must earn an average of at least 90 points on his 5 tests. He scored a total of 384 points on his first 4 tests. Which inequality shows the number of points Matthew may earn on his last test, y, so that he earns an A in the class?

Answer 1

We are going to formulate our inequality based on the equation for calculating average.

Average = Total score / number of tests.

$\begin{gathered} \frac{384+y}{5}\ge90 \\ \frac{384+y}{5}\cdot5\ge90\cdot5\text{ Multiplying both sides by 5} \\ 384+y-384\ge450\text{-384 Subtracting 384 on both sides} \\ y\ge66\text{ Our final Inequality, which is the answer.} \end{gathered}$