SOLUTION: URGENT HELP NEEDED! PLEASE REPLY ASAP! Some of the students were asked how much time they spent revising for the test. 10 students revised for 2.5 hours, 12 students revised fo

Algebra ->  Probability-and-statistics -> SOLUTION: URGENT HELP NEEDED! PLEASE REPLY ASAP! Some of the students were asked how much time they spent revising for the test. 10 students revised for 2.5 hours, 12 students revised fo      Log On


   



Question 872516: URGENT HELP NEEDED! PLEASE REPLY ASAP!
Some of the students were asked how much time they spent revising for the test.
10 students revised for 2.5 hours, 12 students revised for 3 hours and "n" students revised for 4 hours.
The mean time that these students spent revising was 3.1 hours.
Find n.

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!

Hi
%2810%2A2.5+%2B+12%2A3+%2B+4n%29%2F%28n+%2B22%29+=+3.1
%2825+%2B+36+%2B+4n+%29%2F%28n+%2B22%29+=+3.1
61 + 4n = 3.1n + 68.2
.9n = 7.2
n = 8