Test: Range - GMAT MCQ

Set X = {11, 13, 17,............., 83, 89, 97}
Set Y = {5, 15, 25,..............., 75, 85, 95}

Combining two sets, say Set Z

Set Z = {5, 11, 13, 15, 17, 25,..................., 75, 83, 85, 89, 95, 97}

Range = Max Value - Min Value
Range (Z) = 97 - 5 = 92

Range before transaction:
112-45=67
Range after transaction:
(94+24)-(56-20)=118-36=82 
The difference is: 82-67=15
Answer is D

Prior to median 25, there are 7 numbers. 
To make the greatest number as greater as possible, these 7 numbers should cost the range as little as possible. They will be, 24, 23, 22, 21, 20, 19, 18.
So, the greatest value that can fulfill the range is: 18+25=43

The range is the highest value number minus the lowest value number in a sorted data set:
1,2,8,9,7,4,1,1,3,2,3
We need to sort the data set:
1,1,1,2,2,3,3,4,7,8,9
range=9−1=8

The numbers in the "stem" of this display represent tens digits of the test scores, and the numbers in the "leaves" represent the units digits. This stem-and-leaf display represents twenty scores.

The interquartile range is the difference of the third and first quartiles.

The third quartile is the median of the upper half, or the upper ten scores. This is the arithmetic mean of the fifth- and sixth-highest scores. These scores are 73 and 69, so the mean is (73+69)÷2=71. 

The first quartile is the median of the lower half, or the lower ten scores. This is the arithmetic mean of the fifth- and sixth-lowest scores. Both of these scores are the same, however - 57.

The interquartile range is therefore the difference of these numbers: 71−57=14