The postal service sorts mail as Priority Mail Express Prior

The postal service sorts mail as Priority Mail Express, Priority Mail, First-Class Mail, or Standard Mail. Over a period of 3 weeks, 20 of each type were mailed from the Network Distribution Center in Altanta, Georgia, to Des Moines, Iowa. The total delivery time in days was recorded. Minitab was used to perform the ANOVA. The results follow:

Using the ANOVA results, compare the average delivery times of the four different types of mail.

What is the decision rule? Use the 0.01 significance level. (Round your answer to 2 decimal places.)

What is the critical F value for a sample of 16 observations in the numerator and 10 in the denominator? Use a two-tailed test and the 0.02 significance level. (Round your answer to 2 decimal places.)

Solution

Here,

df1 = 3
df2 = 76

Thus, the critical F value is, at 0.01 level, by table/technology,

Reject Ho if F > 4.05. [ANSWER]

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Here,

df1 = n1 - 1 = 16 - 1 = 15
df2 = n2 - 1 = 10 - 1 = 9

Thus, at 0.02 level, two tailed, by table/technology,

F value = 4.96 [ANSWER]