Are there 3 or 4 quartiles? 99 or 100 percentiles?

Question

So I understand that a quartile is a quantile where the data is divided into four groups. 1 2 3 ---|---|---|--- And 1, 2, and 3 are the quartiles. The second quartile is the median, etc. But while studying for the GRE, I read this as part of the answer solution to a question: > From this you can conclude that the word quartile refers to one of the four groups that is created by listing the data in increasing order and then dividing the data into four groups of equal size. Which indicates that *these* are the quartiles:

Answer 1

It could be either.

It could refer to the specific range of the data, e.g., you are in the third quartile.

Or it could refer to the number the locates the quartile, e.g., 7 is the third quartile.

The same applies to percentiles.