SOLUTION: The manager for a large shopping mall believes that visitors to the mall spend, on average, 85 minutes in the mall on any one occasion. To test this belief, the manager commissio

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Question 1186334: The manager for a large shopping mall believes that visitors to the mall spend, on average,
85 minutes in the mall on any one occasion. To test this belief, the manager commissioned
a study which found that, from a random sample of 132 visitors to the mall, the average
visiting time to the mall was 80.5 minutes. Assume that the population standard deviation is
25 minutes and the visiting time is approximately normally distributed.
a) Formulate a suitable null and alternative hypotheses for this test situation.
c) Conduct the appropriate statistical test, at 5% level of significance, to support or
refute the manager’s belief. What management conclusion would be drawn from the
findings?

Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
Ho: t=85 min
Ha: t NE 85 min
alpha=0.05 p{reject Ho|Ho true}
test stat is a z
critical value is |z|>1.96
test stat is z=(x bar=mean)/sigma/sqrt(n)
=(80.5-85)/25/sqrt(135)
=-4.5*sqrt(135)/25=-2.09
reject Ho,the true time is not 85 minutes but is fewer.
p-value=0.036.