Median problem from GMAT PREP. Plz help.

ok24by7 · Last edited by ok24by7 on Sun Aug 31, 2008 10:40 am; edited 1 time in total

How to solve this attached problem?
Attch added again..............

Thanks.

sudhir3127

Mpalmer22 · Posted: Fri Sep 05, 2008 1:09 pm Post subject:

Think of the median as the middle number not as the average. The question is phrased difficultly in that it seems like it is telling you the median number is 73.

For example the median of this set of numbers:
1,2,3,4,4,4,4 is 4 b/c it is in the middle of the set.
However, if the set was:
1,2,3,4,4,4 is 3.5 b/c when you have an even number in the data set, you average the middle 2 numbers to get the median.

The problem you posted is a little tricky since it seems like the median would be closer to the average, but it is the middle number instead. I like to cross a numbers off of each end until if find the middle, and by doing that you see that the majority of the numbers are concentrated to the higher end.

Let me know if you need any more help on that.

sg4931 · Posted: Mon Sep 08, 2008 3:10 pm Post subject:

There are 73 individual scores in total. Call them -- S1, S2,S3........S73.

Rewrite the score table as follows:
50 - 59 : S1, S2
60 - 69 : S3, S4,..,S12
70 - 79 : S13,S14,...S28
80 - 89 : S29, S30,...S37,...S55

The median score is S37 (37th score is the mid point of 73 scores)

Looking at the table above, 37th score falls in the 80 - 89 interval

This how i have understood it. A tricky question indeed!

kaur21 · Posted: Tue Sep 09, 2008 9:22 am Post subject:

Fundamentally, this question will be solved by calculating cumulative frequency.

dally_gmat · Posted: Thu Sep 18, 2008 7:43 pm Post subject:

I lay my cards on same explanation as given below..

robzoc · Posted: Tue Sep 23, 2008 8:38 am Post subject: time

some times ( like this one) i believe that it´s better to number all the scores like:

1 for 50-59
2 for 60-69
3 for 70-79
4 for 80-89
5 for 90-99

of course in the heat of the moment this will be something like (1,2,3,4,5)

112222222222333333333333333444444444444444444444444444444444444444444444555555555555555555555555

count 37 digits and you will find the right interval !

artistocrat · Posted: Mon Oct 06, 2008 3:26 pm Post subject: simplify

Easiest solution. How many scores? 73. The median will be the 37th value. (36 below and 36 above). The 37th value is in the 4th score interval, 80-89.

nicks · Posted: Sun Oct 12, 2008 9:45 pm Post subject:

How I solved it:

Add up total number of scores and divide by 2 (73/2 = 36.5)

Which one has the 36.5th number in it?

50-59 has numbers 1-2
60-69 has numbers 3-12
70-79 has numbers 13-28
80-89 has numbers 29-55
90-99 has numbers 56-73

29 < 36.5 < 55