Question

A local retailer claims that the mean waiting time is less than 7 minutes. A random sample of 20 waiting times has a mean of 5.5 minutes with a standard deviation of 2.1 minutes. At α = 0.01, test the retailer's claim. Assume the distribution is normally distributed. Round the test statistic to the nearest thousandth.

a) State the Null and Alternate Hypotheses.

b) Is this a left, right or two-tailed test?

c) Find the sample test statistic.

d) Use either the P-value or Critical Value approach to conclude your test.

e) State your conclusion in the CONTEXT of the problem.

Answer #1

a)

null hypothesis: | μ | = | 7 | ||

Alternate Hypothesis: | μ | < | 7 |

b)this is left tailed test

c)

sample test statistic t=-3.194

d)

as p value is less than 0.01 level or test statistic is in critical region we reject null hypothesis

e)

we have sufficient evidence at 0.01 level to conclude that mean waiting time is less than 7 minutes

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