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The manager of an assembly process wants to determine whether or not the number

ID: 3150937 • Letter: T

Question

The manager of an assembly process wants to determine whether or not the number of defective articles manufactured depends on the day of the week the articles are produced. She collected the following information. Is there sufficient evidence to reject the hypothesis that the number of defective articles is independent of the day of the week on which they are produced? Use = 0.05.

(a) Find the test statistic. (Give your answer correct to two decimal places.)


(ii) Find the p-value. (Give your answer bounds exactly.)
_________ < p < ______

Day of Week M Tu W Th F Nondefective 88 94 94 94 92 Defective 14 15 13 4 7

Explanation / Answer

Difference Scores Calculations

Treatment 1

N1: 5
df1 = N - 1 = 5 - 1 = 4
M1: 92.4
SS1: 27.2
s21 = SS1(N - 1) = 27.2(5-1) = 6.8


Treatment 2

N2: 5
df2 = N - 1 = 5 - 1 = 4
M2: 10.6
SS2: 93.2
s22 = SS2(N - 1) = 93.2(5-1) = 23.3


T-value Calculation

s2p = ((df1(df1 + df2)) * s21) + ((df2(df2+ df2)) * s22) = ((48) * 6.8) + ((48) * 23.3) = 15.05

s2M1 = s2pN1 = 15.055 = 3.01
s2M2 = s2pN2 = 15.055 = 3.01

t = (M1 - M2)(s2M1 + s2M2) = 81.86.02 = 33.34

The t-value is 33.33919. The p-value is < .00001. The result is significant at p < .05.