Question

Your grades on 4 math tests are 79, 85,

86, and 88. You want your mean grade to
be at least 85. What grade on your fifth
test will give you a mean score of at least
85?

Answer 1

The grade on the fifth test that will give you a mean score of at least 85 is 87

Explanation:

From the question, the grades on 4 math tests are 79,85,86, and 88.

To determine the grade on the fifth test that will give a mean score of at least 85,

Let the grade on the fifth test be x,

From the formula for mean

Mean = Sum of terms / Number of terms

That is,

85 = (79 + 85 + 86 + 88 + x) / 5

`85 = (79 + 85 + 86 + 88 + x)/(5)`

`85 = (338 + x)/(5)`

`338 + x = 85 * 5`

`338 + x = 425\\`

`x = 425 - 338`

`x = 87`

x = 87

Hence, the grade on the fifth test that will give you a mean score of at least 85 is 87.