How does percentile work?

Percentile is a common way to report scores. It reflects how highly someone ranks relative to everyone else in the group.

When you take a group and arrange their score from low to high then divide the group into 100 equal subgroups, the group that an individual belongs to is the percentile.

Generally in score reporting the meaning of percentile is an abbreviation of "better than ___ percentile". For example, 40th percentile means the individual scored better than 40% of the people in the group. So that is better than 30th percentile.

Occasionally percentile is used slightly differently. For example, you may receive a score that says you are the top 1 percentile of the people who took the SAT. That means you are that top 1% and you are better than 99% of the people who took it.

Percentiles are 'created' when large scale studies are done on thousands of babies who are at a certain age. They measure every single baby at each age, and plot their measurements on a chart. A sufficiently large number are measured that these measurements can be seen as indicative of the general population. Then when you take your baby in to be weighed, and the weight is 50th percentile, what that means is that 50% of babies in the original study had a weight that was equal to or less than that weight. The other 50% had a weight that was more than that weight. So the 50th line is really an average line. The 75th suggests a larger than average measurement.

Which is better if u get the ff. % in an exam 40% or 30%