Brand Weeks of Wear A 3 4 6 3 4 B 2 3 2 5 2 C 5 7 5 4 6 4. A dentist is trying t

Question

Brand Weeks of Wear
A 3 4 6 3 4
B 2 3 2 5 2
C 5 7 5 4 6



4. A dentist is trying to decide if there is a difference in the number of weeks three different toothbrushes last. Fifteen patients were randomly assigned to three brands of toothbrushes and the number of weeks that the toothbrushes lasted is given. At the 0.05 significance level, is there a difference in the mean length of time the toothbrushes lasted?

a. State the null and alternate hypotheses.

H0: ________________________________________
H1: ________________________________________

b. State the decision rule.
__________________________________________________________

c. Compute the value of the test statistic.

Analysis of Variance
Source DF SS MS
Factor 2 16.93 8.47
Error 12 18.00 1.50
Total 14 34.93

d. What is your decision regarding the null hypothesis? Interpret the result.

________________________________________________________________________

Explanation / Answer

Ho: Mean A= Mean B=Mean C Ha: At least one mean is different from the others Decision rule: P value of test statistic .05, do not reject. Test statistic F= 8.47/1.50= 5.65 Degrees of freedom numerator 2, denominator 12. P value from F table .01

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