GMATPASSION wrote:
Three people each took 5 tests. If the ranges of their scores in the 5 practice tests were 17, 28 and 35, what is the minimum possible range in scores of the three test-takers?
A. 17
B. 28
C. 35
D. 45
E. 80
Min possible range. That means the lowest possible difference in total 15 values.
0 0 0 0 17
0 0 0 0 28
0 0 0 0 35
Minimum possible range is 35. Oh got the trick.
But my question is If I am thrown a question like this in the test I might panic & try many different kind of values. Is there a particular strategy or pattern for this type of questions.
Try to look at it as overlapping sets problem:
# of people in group A is 17;
# of people in group B is 28;
# of people in group C is 35;
What is the minimum # of total people possible in all 3 groups? Clearly if two smaller groups A and B are subsets of bigger group C (so if all people who are in A are also in C and all people who are in B are also in C), then total # of people in all 3 groups will be 35. Minimum # of total people can not possibly be less than 35 since there are already 35 people in group C.
Answer: C.
Hope it's clear.
P.S. Notice that max range for the original question is not limited when the max # of people in all 3 groups for revised question is 17+28+35 (in case there is 0 overlap between the 3 groups).
Sorry Bunuel but I am still not convinced by this explanation..... for example if you have the following votes:
You would have range 35 for third group, but the range of all three groups would be 39-1= 38 > 35 ?