MacFauz wrote:

vinnik wrote:

On a recent test, Kevin scored m percent higher than the class average, while Katherine scored n percent higher than the class average. What was the class average?

(1) n – m = 7

(2) m = 12

Please explain

Thanks & Regards

Vinni

1) We do not get any useful data from this. Obviously insufficient.

2) We do not get any useful data from this. Obviously insufficient.

1 & 2 together. m = 12% and n = 19%. We still do not have any idea about the class average. Insufficient.

I find it hard to explain why 1 & 2 are "obviously" insufficient. If you could tell me how one could think them to be sufficient, I'll try my best to provide an explanation.

We need a starting point (a score) in order to be able to deduce actual numbers from percentages.

It's the classic "given a percentage, find the number" type of question I think. Hence,

obviously we can't deduce anything from 1+2.