Example of a histogram with fitted normal distribution

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 histogram to evaluate the distribution and adds a fitted normal distribution to check for normality.

  1. Open the sample data, FatContent.MTW.
  2. Choose Graphs > Histogram > Single Y Variable: Simple.
  3. In Y variable, enter Percent Fat.
  4. Click OK.
  5. Click the graph to select it, then click the plus sign beside the graph to open the Graph Elements menu.
  6. Select Distribution Fit.

Interpret the results

The heights of the bars follow the shape of the fitted distribution line relatively closely. 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
Anderson-Darling Test
AD-Value
P-Value
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