A scientist for a company that manufactures processed food wants to assess the percentage of fat in the company's bottled sauce. The advertised percentage is 15%. The scientist measures the percentage of fat in 20 random samples. Previous measurements found that the population standard deviation is 2.6%.

As part of the initial investigation, the scientist creates a probability plot to check for normality and to evaluate the distribution.

Choose Graphs > Probability Plot > Single Y Variable: Simple.

In Y variable, enter Percent Fat.

Click OK.

Interpret the results

The data points are relatively close to the fitted normal distribution line. The p-value is greater than the significance level of 0.05. Therefore, the scientist fails to reject the null hypothesis that the data follow a normal distribution.

Summary Statistics

N

Mean

StDev

Minimum

Maximum

20

16.4600

2.2582

12.3000

20.0000

Anderson-Darling Test

Null hypothesis

H₀: Data follow a normal distribution

Alternative hypothesis

H₁: Data do not follow a normal distribution

AD-Value

P-Value

0.34

0.4631

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