After five tests Allison's average score was 88. After six tests her average score had increased to 90. What was her score on the sixth test?

100

Step-by-step explanation:

After five test, Allison's average score was 88. Let the total of her score be x

x/5=88

Cross multiply

x=88 (5)

x=440

The total scores of the five test was 440.

After the sixth test, her acreage score became 90. Let the total score again be x

x/6=90

Cross multiply

x=90 (6)

x=540

The sixth score is 540-440=100

Sixth test was 100

Step-by-step explanation:

5 tests average is 88 - An equation for the average is ...

5x/5 = 88 (where x is 88) so it can also be 440/5 = 88 and this is correct

The sixth test has to be greater than 88 as the average increases; an equasion for this is ...

Let y = the sixth test result

Let x = the previous average; 88

(5x + y) / 6 = 90 (the new average)

5x + y = 540

As said before 5x = 440 so we can substitude 440 into 5x

440 + y = 540 (-440)

y = 100

So, the equation shows that the 6th test result is 100 but we should check to see if this is correct so ...

440 + 100 = 540

540 / 6 = 90 (so we are correct!)