WP books p68/108 Corrections on Weighted average

[AnnaC666]

Hello,

As per the correction of the question 2 on problem set p 68/108 could you please further explain why the 1*m+2*4 must offset so that we can find m = -8?

Many thanks

Regards

Anna

[Sage Pearce-Higgins]

I assume you're referring to question 2 from the Weighted Averages problem set (p99 in the paper copy) in the 6th edition of the WP strategy guide. I can't find the correction that you refer to.

For this kind of problem, you can think of an average as the fulcrum point around which the numbers of a set are balanced. (To take a simple example, the "fulcrum point" of the numbers 1 and 7 would be 4). In this case, we know that the fulcrum point is 66 and that the women in the group are higher than that, at 70 tickets each. Each woman is selling 4 tickets more than average. Since we have just 1 man for every 2 women, each man must sell 8 tickets lower than the average to balance things out.

Try drawing this out as a fulcrum and it might be clearer. Plus we could use smart numbers and assume that the group contains just 1 man and 2 women.