Percentile problems: new kinda Q in GRE

[dknight237]

Col B is bigger, area under the curve is bigger

[Sadistic Sponge]

I think it is D, as we have no idea what the standard deviation is or any information on the shape of the curve.

[tommytommy]

Originally Posted by sweetu1995

Ok. got it. But can I safely conclude that 50th percentile is the median ?

Yes, whether the distribution is normal or abnormal 50th percentile is the median. as median is the value of the middlemost number in a set arranged in ascending order. It has exactly the same no. of observations before and after.

[susangre]

Where can i find this type of problems to practice

[hahahuhut]

50 is 50th percentile, then 12 (62-50) take 10th (60th-50th) percentile, so another 12 will take less than 10th percentile, so 74 is less than 70th percentile,

answer is B

[mlkovach]

There are 10,000 numbers, ranging from 20 to 80. If 62 is 60th percentile, then
Col A: What percentile is 74
Col B: 70th percentile

answer: D

We have no information on the distribution.

Consider some set with 6,000 20's , 62, 3,998 63's, 74 (74=99%tile)

compared to 6,000 20's , 62, 74, 3,998 80's... (74=61%tile)

[tommytommy]

Originally Posted by mlkovach

There are 10,000 numbers, ranging from 20 to 80. If 62 is 60th percentile, then
Col A: What percentile is 74
Col B: 70th percentile

answer: D

We have no information on the distribution.

Consider some set with 6,000 20's , 62, 3,998 63's, 74 (74=99%tile)

compared to 6,000 20's , 62, 74, 3,998 80's... (74=61%tile)

Are we not supposed to assume normal distribution for all percentile & SD questions for GRE?

[mlkovach]

I don't recall seeing that in the instructions...