Jameson received four grades on his algebra tests, bringing his average to an 88 for that class. What grade would he have to have on his last test in order to bring his average up to 90?
Jameson needs to make
Let's let each of the test grades be represented by
The average of the first four tests is
Jameson would like the final average of the five tests to be
We notice that this average contains the sum of
We can now substitute this into the average of the five tests
So Jameson needs to make
Jameson needs 98 on the next test.
From this we can can see that
The mean of 4 tests is
If the mean of 5 tests is
The difference between the two totals is how much Jameson needs to score on the next test to average 90.