So I know how to calculate percentile on a simple data set:
lets say student grades are 38, 47, 49, 58, 60, 65, 70, 79, 80, 92
Number of scores below 70 = 6
Using the percentile formula,
Percentile = (Number of Values Below “x” / Total Number of Values) × 100
Percentile of 70
= (6/10) × 100
= 0.6 × 100 = 60
Therefore, the percentile for score 70 = 60%
But how to do percentile calculation on accumulated data?
Say for example a school with 3000 students
And this is the data table showing how many students finished a test in how many minutes
For example 10 students finished the test in 15 min
And 1000 students finished the test in 30min
And 1410 students finished the test in 40min (or more)
num students , how long to finish the test:
----------------------
10 15min
80 20min
500 22min
1000 30min
1410 40min+
total: 3000
How to calculate the percentile when using group of data like that?