GRE Math Guide 5, Chapter 10, Medium Practice Set Questions

[franalej]

In GRE Math Guide 5, Chapter 10, medium practice set question number 19, the following problem is presented:

In a recreation club with 212 members, 130 participate in kickboxing, and 110 participate in rowing. If at least 10% of the club's members participate in neither kickboxing nor rowing, what's the minimum number of members who participate in both?

In developing your answer, the solution assumes that the "at least 10% of the club's members who participate in neither kickboxing nor rowing" is equal to 22. However, calculating 10% of 212 is equal to 21.2 people. I understand that there are no fraction people possible, so 21.2 must be rounded to the nearest integer. However, the rule of rounding states that numbers which are x.1 up to x.4 round down to x, while numbers which are x.5 up to x.9 round up to x+1, where x is a positive integer. Why do you round the number 21.2, which is positive, to the higher integer 22.0 instead of to 21.0?

Thanks

-f

[my.dam]

because 21 would represent less than 10% of members who belong to neither of the groups, which contradicts the "minimum 10%" given in the question. Hope that helps.

[franalej]

But of course! thanks a lot my.dam :)

-f

because 21 would represent less than 10% of members who belong to neither of the groups, which contradicts the "minimum 10%" given in the question. Hope that helps.

[tommywallach]

Well done, My dam. That's absolutely right!

-t