SOLUTION: To encourage telephone efficiency, a catalog call center issues a guideline that at least half of all telephone orders should be completed within 2 minutes. Subsequently, a random

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Question 257875: To encourage telephone efficiency, a catalog call center issues a guideline that at least half of all telephone orders should be completed within 2 minutes. Subsequently, a random sample of 64 telephone calls showed that 40 calls lasted over 2 minutes. (a) At α = .05 is this a significant departure from the guideline in a right-tailed test? State your hypotheses and decision rule. (b) Find the p-value. (c) Is the difference important (as opposed to significant)?
Answer by stanbon(75887) About Me  (Show Source):
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To encourage telephone efficiency, a catalog call center issues a guideline that at least half of all telephone orders should be completed within 2 minutes. Subsequently, a random sample of 64 telephone calls showed that 40 calls lasted over 2 minutes.
(a) At α = .05 is this a significant departure from the guideline in a right-tailed test? State your hypotheses and decision rule.
Ho: p <=0.5
Ha: p >2
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Rule: Reject Ho if the test stat is greater than invNorm(0.95)= 1.645..
Test Stat: z(40/64)= (0.625-0.5)/sqrt(0.5*0.5/64)= 2
(b) Find the p-value = P(z>2) = 0.0228..
(c) Is the difference important (as opposed to significant)?
Yes.
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Cheers,
Stan H.