John’s current average after 5 grades is 80, what must he earn on his next test to raise his average up to an 82? .

Question

Thanks alot!

Answer 1

The average is the sum of grades divided by number of grades.

 

sum / 5 = 80                          eq1

 

(sum + x) / 6 = 82                  eq2

 

 

The first equation shows the first average.  The second equation shows the average when taking the next test into account of the grades he has already earned.  If we solve for the sum in the first equation, we get that sum is 400.  Using this sum in the new average, we can solve for x, which is the next grade he needs to get if he wants to get an 82 average.

 

(400 + x) / 6 = 82

 

400 + x = 492

 

          x = 92

 

He needs to earn a 92 on the next test.