Need Help with Median related problem from GmatPrep

Expert replies

ildude02: Master | Next Rank: 500 Posts; Posts: 320; Joined: Sun Jan 13, 2008 10:00 pm; Thanked: 10 times

by ildude02 » Mon Jan 14, 2008 12:57 pm

I ran into this problem on the practice test. I'd really appreciate if anyone can solve this problem.

The table below shows the distribution of test scores to a grioup of management trainees. Which score interval contains the median of the 73 scores?

---------------------------------------
Score / No of Scores
Interval
-----------------------------------------
50-59 / 2
60-69 / 10
70-79 / 16
80-89 / 27
90-99 / 18
-------------------------------------------

(a)60-69 (b)70-79 (c) 80-89 (d)90-99 (e) cannot be determined.

I chose option b but the answer was option c.

Source: Beat The GMAT — Problem Solving | Mon Jan 14, 2008 12:57 pm

StarDust845: Master | Next Rank: 500 Posts; Posts: 158; Joined: Mon Dec 03, 2007 8:32 am; Thanked: 7 times

by StarDust845 » Mon Jan 14, 2008 1:25 pm

If you think of it, the median is the middle score (odd number of elements in the set) of 73 scores, when the latter is arranged in ascending order.

So the 37th score falls in option C range.

Calista.

mollyrg: Junior | Next Rank: 30 Posts; Posts: 17; Joined: Mon Nov 26, 2007 7:14 pm

pls elaborate the explaination

by mollyrg » Mon Jan 14, 2008 2:50 pm

pls elaborate the explanation of the ans

Thanks

StarDust845: Master | Next Rank: 500 Posts; Posts: 158; Joined: Mon Dec 03, 2007 8:32 am; Thanked: 7 times

by StarDust845 » Mon Jan 14, 2008 3:01 pm

Here is a simpler example.

Let the following be scores.

2,2,3,3,3,4,5,6,6 (9 numbers).

What's the median? It is the 5th (middle of 9 numbers) number , i.e. 3.

Similarly in the question given, we have to find the middle number of 73 numbers and it is given that theer are 2 numbers between 50 and 59, 10 numbers between 60 and 69 etc.

So the 37th (middle of 73) number will come in 80-89 range.

Calista.

ildude02: Master | Next Rank: 500 Posts; Posts: 320; Joined: Sun Jan 13, 2008 10:00 pm; Thanked: 10 times

by ildude02 » Mon Jan 14, 2008 4:41 pm

Calista, thanks for the response. Apparently, I mis-interpreted the question and it never struck to me that the question was reffering to 73 "number" of scores with 37th score as the median. It makes sense now.

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