median in triangle

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median in triangle

by marmar29 » Fri Aug 19, 2011 12:34 pm
if tri. ABC, has median from ad = 6 cm & n is the center of all medians
so an = ........
a 2
b 3
c 4
d 5
it comes the right ansser 4 but i dnt knw how
can u help ??
thanks
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by Anurag@Gurome » Fri Aug 19, 2011 7:58 pm
marmar29 wrote:if tri. ABC, has median from ad = 6 cm & n is the center of all medians
so an = ........
a 2
b 3
c 4
d 5
I also suggest you to check your source. The reasons are in most of the cases (in other threads) the right answer is not in the option, wordings of the problems are not standard and GMAT questions always have 5 options.

In this problem, 'center of all medians' does not make any sense. The point where all medians of a triangle intersect is known as the the centroid of the triangle. At the centroid every median is divided in 2:1 ratio. Here, AD is the median from A and N is the centroid of the triangle. Hence, AN:ND = 2:1

Thus, AN = (2/3)*AD = (2/3)*6 = 4

The correct answer is C.
Anurag Mairal, Ph.D., MBA
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Gurome, Inc.
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