Answer :
Answer:
The grade on the fifth test that will give you a mean score of at least 85 is 87
Step-by-step 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
[tex]85 = \frac{79 + 85 + 86 + 88 + x}{5}[/tex]
[tex]85 = \frac{338 + x}{5}[/tex]
[tex]338 + x = 85 \times 5[/tex]
[tex]338 + x = 425\\[/tex]
[tex]x = 425 - 338[/tex]
[tex]x = 87[/tex]
x = 87
Hence, the grade on the fifth test that will give you a mean score of at least 85 is 87.