Answer:
He must score an 86 or more on his third test.
Step-by-step explanation:
An average is calculated by the sum of the numbers divided by the total number (#) of numbers (if that makes sense). Knowing this, we can write an algebraic equation in order to find the answer. Let x equal the unknown number.
John's previous test scores and this test score now must be at least an average of 90 or more. Therefore, the equation would be [tex]\frac{86+98+x}{3} \geq 90[/tex]. Isolate x to find the answer:
[tex]\frac{86+98+x}{3}\geq 90\\ \frac{184+x}{3} \geq 90\\184 + x \geq 270\\x \geq 86[/tex]
Therefore, he needs to get at least a 86 or higher.
