Skylar's grades on four math tests are 85, 78, 77, and 69. What does Skylar need to score on the next test in order to have a mean score of 80?
83
90
91

Question

Skylar's grades on four math tests are 85, 78, 77, and 69. What does Skylar need to score on the next test in order to have a mean score of 80?
83
90
91

parthkohli · Answer

Do you know how to solve equations?

parthkohli · Answer

If you need a hint, just mention me in the replies.

parthkohli · Answer

$\Large \color{purple}{\rightarrow {x + 85 + 78 + 77 + 69 \over 5} = 80 }$

Challenge to solve for x, where x will be the answer!

anonymous · Answer

wait what?

anonymous · Answer

91

parthkohli · Answer

You have to find the value of x in the equation. It's because x is a number we don't know so we can put it as a variable. Now, if you know the formula, then you know why put that equation.

parthkohli · Answer

$\Large \color{purple}{\rightarrow x + 85 + 78 + 77 + 69 = 400 }$

$\Large \color{purple}{\rightarrow x + 309 = 400 }$

$\Large \color{purple}{\rightarrow x = 91 }$

YES!