Will u help with my math

On mr.robinsons last history test for tie marking period the average score was 98. Forty students took the test, 39 students scored 100. What was the score of the student who did not score 100 on the test? EXPLAIN HOW U GOT UR ABSWER

You know that to get an average you take the total scores of all of the children and then divide them by the total number of children. From this we get:

(39*100 + x)/40 = 98
39*100 + x = 3920
3900 + x = 3920
x = 20

You can check this by adding the scores and then re-dividing:
(39*100 + 20)/40 = 98

Hope this helped!

Please don't use text speak here, it makes things harder than they need to be.

98 is the average. To find the average you take total earned scores and divide by total possible.
The total possible was 100 per person, with forty people you multiply and get 4,000.
So you want to know the total value, since everyone but one person got all possible points the total possible-the total earned = the number of points that one student missed.So you have 98/100, you want the denominator to be 4000, so you multiply by 40 (also the number of tests take or students) you come up with 3920/4000. Now subract 3920 from 4000 to get your answer. The student missed 80. so out of 100 possible points they missed 80, ending up with 20. They scored 20/100.

If you multiply SCORE times Number of students and then add SCORE (unknown) of the alone student, total must be equal to the AVERAGE times TOTAL STUDENTS.

100 * 39 + x = 98 * 40
3900 + x = 3920
x = 3920 - 3900 = 20


The only student scored 20

40 students: average 98

so total score of 40 is 40 x 98 = 3920

But 39 scored 100: so 100 X 39 = 3900

3920-3900= 20

one student scored 20

got it?

40 X 98 = 3920

39 X 100 = 3900

3920 - 3900 = 20 marks ANSWER

N + (40 -- 1)(100) = 40(98) whence N = 40*98 -- 39*100 = 20
that one scored 20 only