# Problem 1.1| Introduction to Statistics and Data Analysis| Probability & Statistics for Engineers & Scientists 8th Ed| Walpole, Myers, Myers, Ye

#### (e) Compute the 20% trimmed mean for the above data set.

SOLUTION:

Part a

The sample size is 15.

Part b

$\overline{x}=\frac{1}{15}\left(3.4+2.5+4.8+2.9+3.6+2.8+3.3+5.6+3.7+2.8+4.4+4.0+5.2+3.0+4.8\right)$

$\overline{x}=3.787$

Part c

Sample median is the 8th value, after the data is sorted from smallest to largest: 3.6.

Part d

A dotplot is shown below

Part e

After trimming total 40% of the data (20% highest and 20% lowest), the data becomes: 2.9, 3.0, 3.3, 3.4, 3.6, 3.7, 4.0, 4.4, 4.8

So. the trimmed mean is

$\overline{x}=\frac{1}{9}\left(2.9+3.0+3.3+3.4+3.6+3.7+4.0+4.4+4.8\right)$

$\overline{x}=3.678$