Question

Justin earned scores of 85, 92, and 95 on his science tests. What does he need
to earn on his next science test to have an average (arithmetic mean) of 93%?

Answer 1

Answer:

Justine needs to score a 100 to have an average of 93%.

Step-by-step explanation:

Given:

Justin scores 85, 92 and 95 on his science tests.

To find:

The score that he needs to earn to have an average of 93%?

Solution:

Let the score in next science test = $x$

Formula for Average/Arithmetic Mean is given as:

$Average = \dfrac{\text{Sum of all observations}}{\text{Total number of observations}}$

Here we have 4 number of total observations and average is 93%.

Now, put all the values here:

$93 = \dfrac{85 +92+ 95+x}{4}\\\Rightarrow 93\times 4=85 +92+ 95+x\\\Rightarrow 372=272+x\\\Rightarrow x = 372-272\\\Rightarrow x = 100$

So, Justin needs to score 100 to have an average of 93%.