A percentile for ungrouped data is a value that divides the data into 100 equal parts. For example, the 50th percentile is the median of the data, which means that 50% of the data values are below or equal to it. To find a percentile for ungrouped data, we can use the formula:
P = L + (n/100) * i
where P is the percentile value, L is the lower limit of the class interval containing the percentile, n is the cumulative frequency of the class interval containing the percentile, and i is the width of the class interval.
2. PERCENTILE
A percentile is a certain percentage of a set of data.
Percentiles are used to observe how many of a given
set of data fall within a certain percentage range;
For example;
A thirtieth percentile indicates data that lies the 13%
mark of the entire data set.
2
5. EXAMPLE 1 5
Find the 30th percentile (P30) of the following scores 35, 42, 40, 28, 15,
23, 33, 20, 18, and 28.
Step 1: arrange the scores in increasing order
15 18 20 23 28 28 33 35 40 42
𝑃30 =
30
100
(N+1)
Step 2: solve for P30 which is actually the same with D3
=
30
100
(10+1)
=
33
10
= 3.3 𝑜𝑟 3
=
30
100
(11)
P30 is the 3rd element in the
scores15 18 20 23 28 28 33 35
40 42
