The scores listed below are the results from students taking a dexterity test. what is the 75th percentile of these scores?

1, 1, 1, 1.5, 2, 2, 2, 2.5, 3

The 75th percentile is also called the 3rd quartile.

First find the median, since this is an odd number of elements it is simply the middle term (if there are an even number of terms it will be the average of the two middle terms) which in this case is 2.

Now find the median term between 2 and the last term, in this there are an even number of terms so it will be the average of the two middle terms 2 and 2.5, which is:
2.25