SOLUTION: Hi, here is the question: The average (arithmetic mean) of the test scores of a class of p students is 70, and the average of the test scores of a class of n students is 92. Wh

Algebra ->  Average -> SOLUTION: Hi, here is the question: The average (arithmetic mean) of the test scores of a class of p students is 70, and the average of the test scores of a class of n students is 92. Wh      Log On


   



Question 76980: Hi, here is the question:
The average (arithmetic mean) of the test scores of a class of p students is 70, and the average of the test scores of a class of n students is 92. When the scores of both classes are combined, the average score is 86. What is the value of p/n?
I first tried 86=70p + 92n, but quickly realized it wasn't going to work. I don't know how to work it so I can eliminate one of my unknowns and solve for the other. Help! Thanks.

Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
you don't need to know (and don't have enough information to find) the values of p and n...you need to know their ratio

your equation was on track, but the 86 is the combined average...the sums of all the scores (which you did) DIVIDED by the number of scores (which you didn't do)

so...86=%2870p%2B92n%29%2F%28p%2Bn%29...then 86p+86n=70p+92n...so 16p=6n... so p%2Fn=3%2F8