ETS GRE Quantitative Practice pg. 111 #10
Percentiles are a common concept in real life, so learning how to deal with them for the GRE might actually pay dividends later in life. In this video, Vince solves an official ETS GRE math question from the Quantitative Practice book - pg. 111 #10.
You don't really have to know what a normal distribution is for this question, but it couldn't hurt to have seen one before, so you might also benefit from watching this video, in which I explain a question with a normal distribution in it.