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Chapter 2: Q. 11 (page 138)

R2.11 Fruit fly thorax lengths Here are the lengths in millimeters of the thorax for 49 male fruit flies: 18

Are these data approximately Normally distributed? Give appropriate graphical and numerical evidence to support your answer.

- Interpret a Normal probability plot.

Short Answer

Expert verified

These data are, in fact, normally distributed.

Step by step solution

01

Given Information 

The lengths in millimeters of the thorax for 49 male fruit flies: 18

02

Explanation 

In this case, frequency is defined as the number of values that fall within the class interval.

Make sure that the classes do not overlap, and all have the same width (Note: Changing the classes will change the frequency distribution and the histogram).

ClassFrequency
0.6-<0.65
3
0.65-<0.7
3
0.7-<0.75
5
0.75-<0.8
9
0.8-<0.85
17
0.85-<0.9
8
0.9-<0.95
4

Histogram

Each bar needs to have the same width and height, corresponding to the frequency.

03

Explanation 

Follow these steps to make a normal probability plot:

The normal scores are on the vertical axis, while the provided values are on the horizontal axis.

The symmetric histogram and linear normal quantile plot give the distribution a nearly normal form.

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