Answer to Question #294436 in Statistics and Probability for jjh

Question

Use the following cell phone airport data speeds​ (Mbps) from a particular network. Find P80.

Answer 1

Assume the data is:

0.1

0.2

0.3

0.5

0.6

0.6

0.7

0.7

0.8

0.8

0.8

0.8

0.8

0.9

0.9

1.3

1.4

1.5

1.6

1.6

1.6

2.1

2.1

2.4

2.4

2.5

3.4

3.6

4.1

4.2

4.5

4.6

5.7

6.7

7.7

8.1

8.5

12.6

12.6

12.8

12.8

13.3

13.3

13.7

14.2

14.3

15.1

15.5

15.6

28.6

Solution:

The data are in ascending order.

Compute the position of the p^th percentile (index $i$ ):

$$i=\dfrac{p}{100}\times n=\dfrac{80}{100}\times50=40$$

The index $i$ is an integer ⇒ the 80^th percentile is the average of the values in the 39^th and 40^th positions (12.8 and 12.8 respectively)

Answer: the 80^th percentile is (12.8 + 12.8) / 2 = 12.8

P80=1.6 Mbps