Question

Alex scored 98,72, and 87 on his first three math test. What must he score on the next test to have an average of at least 86 (P.S I need quickly no need to rush yourself just quickly)

Answer 1

Answer:

$\huge\boxed{\text{At least an } 87\%}$

Step-by-step explanation:

In order to find what score Alex must earn to have an average of 86 on all his tests, we need to first note what the formula to find the average of a data set is.

$\displaystyle \frac{x_1+x_2+...x_n}{n}$

What the formula means is that we have to add up all the values then divide by the total number of values.

Let's represent our unknown number as $x$.

$\displaystyle \frac{98+72+87+x}{4} \geq 86$ (since we want AT LEAST an 86).

Let's solve this inequality for x.

• $\frac{98+72+87+x}{4} \cdot 4 \geq 86 \cdot 4$
• $98+72+87+x \geq 344$
• $257 + x \geq 344$
• $257 + x - 257 \geq 344 - 257$
• $x \geq 87$

So, Alex must score at least an 87% on his next quiz to have an average of 86%.

Hope this helped!