A boy's test grades are 68 , 72, 78, 80 and 86. What grade must he get on his next test to make his test average exactly 75?
75 * 6 = 450
Add his test scores and subtract from 450.
To find out what grade the boy must get on his next test to make his test average exactly 75, we need to calculate his current average.
To find the average, we add up all the test grades and divide the sum by the number of tests. In this case, the boy has taken 5 tests, so we have:
68 + 72 + 78 + 80 + 86 = 384
Now, we divide the sum by the number of tests:
384 ÷ 5 = 76.8
So, the boy's current average is approximately 76.8.
To calculate the grade the boy must get on his next test to make his average exactly 75, we need to find the difference between 75 and his current average.
75 - 76.8 = -1.8
Since we want the average to be exactly 75, we need to have a positive difference of 1.8. This means the boy needs to improve his average by 1.8.
To achieve this, we add 1.8 to the current average:
76.8 + 1.8 = 78.6
Therefore, the boy must get a grade of 78.6 (or rounded up to the nearest whole number) on his next test to make his test average exactly 75.