 # percentile

I am wondering why D is not correct. I feel both B&D are same. What does it mean to say that an observation falls in the sixty-fifth percentile? A) 35% of all the observations are below that point. B) 65% of all the observations are below that data point. C) 65% of all the observations are above that data point. D) 35% of all the observations are above that data point. Your answer: D was incorrect. The correct answer was B) 65% of all the observations are below that data point.

because the percentile would be 65 plus one point that would mean that 35% - one point would be over if you look at the formula you will understand it says for example that the third quartile is the point below which 75% of observations lie

Try this, along the same lines: Kim Jones is a portfolio manager for a mutual fund. Kim ranks in the top quartile of the fund’s peer group comprising 623 mutual funds. The number of funds whose performance ranked below Kim’s is at least: a. 469 b. 468 c. 467 d. 415 Dreary

i think the answer is C

Nope.

B

Yes, but why?

(n+1)75/100 = 624*75/100 = 468

That’s fine, but the trick was that it asked for funds which ranked below the top quartile. So one way to think of it is to include all the funds that are in the 3rd quartile and lower. The formula you used includes all funds that are below the ones in the top quartile, which is correct. Dreary

I think the pth percentile is any number x so that at least p% of the obs. fall at or below x and at least (100 - p) % fall at or above x. That means D is a fine answer.

No, “d” is way off. Also, you can’t say for example that 40% of the observation fall at or below some x, *and* that 60% fall at or above, because you’d be including some observations in both brackets. Dreary

B) is what the definition of Quantile (including percentile) says, Quantile is the general term for a value at or below which a stated proportion of the data (in this case, 65%) in a distribution lies. But the defintion is assuming the data are sorted in an ascending order…