<p>Pg 835 BB2 # 18</p>
<p>The average 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 us 92. When the scores of both classes are combined, the average score is 86. What is the value of p/n?</p>
<p>I got the correct answer of 3/8, but I'm sure there is a quicker way to solve this than by randomly substituting numbers in for n and p.</p>
<p>(70p + 92n)/(p+n) = 86
70p + 92n = 86p + 86n
6n = 16p
6/16 = p/n
p/n = 3/8</p>
<p>Given that the sum of each class’ scores is 70p and 92n respectively, we can write an equation for the average of both classes together.</p>
<p>Total score sum/# of students = Average
(70p + 92n)/(p + n) = 86
70p + 92n = 86p + 86n
6n = 16p
6 = 16p/n
p/n = 6/16 = 3/8</p>
<p>Makes perfect sense, thanks.</p>