Question

Erika needs a test average of 85 or higher to make the honor roll. • There are four tests in the term. • Her first three test grades were 78, 80, and 88. Which inequality could be used to find what she needs to score on her fourth test, x, in order to make the honor roll?

Answer 1

`x\ge94`

Step-by-step explanation:

Average test score is expressed using the formula;

Average = Sum of the grades/Total number of test

Let x be the grade of the fourth test.

If Erika needs a test average of 85 or higher to make the honor roll, this can be expressed as;

`(78+80+88+x)/(4)\ge85`

Cross multiply

`\begin{gathered} 78\text{ + 80 + 88 +x }\ge4\cdot85 \\ 246\text{ + x}\ge340 \end{gathered}`

Subtract 246 from both sides

`\begin{gathered} 246\text{ + x-246}\ge340-246 \\ x\ge94 \end{gathered}`

Hence the inequality that could be used to find what she needs to score on her fourth test, in order to make the honor roll is

`x\ge94`