A particular automotive electrical fuse is designed to disrupt a circuit at a no
ID: 3126051 • Letter: A
Question
A particular automotive electrical fuse is designed to disrupt a circuit at a nominal current of 10 amps. The mean and variance of the time at 11 amps required to produce a disruption are quality characteristics specified for the proper functioning of the fuse. A sample of 20 such fuses produces a sample standard deviation of 24.1 seconds. The researcher is interested in finding evidence at the .05 level that the standard deviation exceeds 20 seconds.
Which of the following is(are) the correct critical value(s)?
1.729
30.144
27.204
36.191
-1.96, 1.96
a.1.729
b.30.144
c.27.204
d.36.191
e.-1.96, 1.96
Explanation / Answer
Since this is a test of variance, then this is a chi^2 distirbution.
As df = n - 1 = 20 - 1 = 19, and it is at 0.05 level, then using table/technology,
chi^2(crit) = 30.144 [ANSWER, B]
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