A class of 30 students had an average (arithmetic mean) of 92 points on a geography test out of possible 100. If 10 of the students had a perfect score, what was the average score for the remaining students?
a. 58
b. 87
c. 88
d. 90
e. 92
2007-09-10 22:01:12 · 5 answers · asked by king_24680 1 in Science & Mathematics ➔ Mathematics
88.
If the arithmetic mean is 92, that means the total points scored is 30 x 92 = 2760.
If 10 students got perfect scores, then those ten scores added up to 10 x 100 = 1000.
Subtract 2760 - 1000 = 1760 to get the total score of the 20 remaining students.
Divide 1760 by 20 to get the average score of those 20 students. And that average score is 88.
2007-09-10 22:04:16 · answer #1 · answered by SoulDawg 4 UGA 6 · 1⤊ 0⤋
Easy
(1000/10)(10/30) + (X/20)(20/30) = 92
==> X = (92-(1000/30))*30 = 1760
Now
1760/20 = 88
2007-09-10 22:19:59 · answer #2 · answered by Dexter H. 2 · 0⤊ 0⤋
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2016-12-13 05:59:11 · answer #3 · answered by ? 4 · 0⤊ 0⤋
very simple
c.
2007-09-10 22:24:48 · answer #4 · answered by ngtuhanh188 3 · 0⤊ 0⤋
..a.
2007-09-10 22:07:50 · answer #5 · answered by Anonymous · 0⤊ 1⤋