SOLUTION: Mark's average (arithmetic mean) on four tests is 75. What grade does he need on his fifth test to raise his average to an 80?

Algebra ->  Average -> SOLUTION: Mark's average (arithmetic mean) on four tests is 75. What grade does he need on his fifth test to raise his average to an 80?       Log On


   

Question 309319: Mark's average (arithmetic mean) on four tests is 75. What grade does he need on his fifth test to raise his average to an 80?


Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Mark's average (arithmetic mean) on four tests is 75. What grade does he need on his fifth test to raise his average to an 80?
----------------
Let "x" be the score on the 5th test.
---
solve: (4*75+x)/5 = 80
300+x = 400
x = 100 (score needed on the final test)
===========================================
Cheers,
Stan H.
===========================================