Source: Official Guide Revised GRE 1st Ed. Part 6; Set 3; #2

9

In the course of an experiment, 95 measurements

In the course of an experiment, 95 measurements were recorded, and all of the measurements were integers. The 95 measurements were then grouped into 7 measurement intervals. The graph above shows the frequency distribution of the 95 measurements by measurement interval. Quantity A : The average (arithmetic mean) of the 95 measurements Quantity B : The median of the 95 measurements Quantity A is greater., Quantity B is greater., The two quantities are equal., The relationship cannot be determined from the information given.

2 Explanations

2

CHAHAT RUSTAGI

I am really not clear with the MEAN part! Please re-explain.

Jan 19, 2016 • Comment

Cydney Seigerman, Magoosh Tutor

The mean is the average value of a set of numbers. If we have a symmetrical distribution, the average will be close to the median, or middle number, of that distribution. This is what Chris shows when he discusses what is observed in intervals 1-5, 6-10, and 11-15. Because there are 15 measurements in the 1-5 interval and 15 measurements in the 11-15 interval, if we were to ignore the measurements above the 11-15 interval, we could conclude (without doing any calculations) that the mean will be in the 6-10 interval and very close to the median. The mean could be slightly higher or lower or the same as the median, depending on the exact values within the 6-10 interval.

However, in this problem, because there are values above the 11-15 range, we can determine that the average will be skewed to the left, making the average greater than the median.

I hope this helps! :)

And for more review on mean, median, and mode, check out the following post from our GRE blog :D

http://magoosh.com/gre/2014/mean-median-and-mode-on-the-gre/

Jan 21, 2016 • Reply

6

Gravatar Chris Lele, Magoosh Tutor

Oct 7, 2012 • Comment

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