GMAT Math

Hello,

Could anybody explain the solution to the attached problem?

Though I was able to arrive at some answer my approach was very time consuming. Please let me know how the attached problems can be solved quickly.

Thanks,
Shobha

I'm very skeptical about the second question; it says xy = 1, and then asks what 2(x+y)^2/2(x-y)^2 is equal to. Take x = 4 and y = 1/4 for example' xy = 1. (4+1/4)^2 = 18.0625. (4-1/4)^2 = 14.0625. When you divide 18.0625 by 14.0625, you do not get 16. Flag that question for review

1)
For Class A:
Range = r
Greatest Height = g
Hence least height La = g - r ( range = greatest - least)

For Class B:
Range = s
Greatest Height = h
Hence least height Lb = h-s

The statements are:

(1) r<s
(2) g>h

(1) r<s
hence g-r > g-s
But this is not sufficient.

(2)g>h
hence g-r > h-r
But this is not sufficient.

Combining (1) and (2)
g>h
hence g-r > h-r

r<s
Substitute s instead of r on RHS
hence g-r > g-s
So least height of A La > least height of B Lb

So, both (1) and (2) together are sufficient
Answer is C
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3)
imagine the set as { V1, V2, ... V73)
V1 falls in 50-59 etc
Total No of scores = 73
Hence median is (73+1)/2 = 37th score

The 37th value is in 80-89 range.

Hence answer is C