Question

Karinas science test scores for this quarter are 84,86,90 and 68. What score does she need on her fifth science test to get a test average of at least 84

Answer 1

Karina must score atleast 92 on the fifth test to get a average of atleast 84.

Explanation:

We are given the following in the question:

84, 86, 90, 68

We want the average score to be atleast 84.

Let x be the score on fifth test.

Formula:

`Mean = \displaystyle\frac{\text{Sum of all observations}}{\text{Total number of observation}}`

Thus, we can write the equation:

`(84+86+90+68+x)/(5)\geq 84\\\\\Rightarrow 84+86+90+68+x \geq 420\\\Rightarrow 328+x \geq 420\\\Rightarrow x \geq 92`

Thus, Karina must score atleast 92 on the fifth test to get a average of atleast 84.