# Lab Exercise #22.doc - Hypothesis testing exercises Lab...

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Hypothesis testing exercisesLab Exercise# 22 Hypothesis tests about the mean and proportion, p-values.1.The personnel manager suspects there is a higher than average level of absenteeism on Mondays. He knowsthat the average absentee rate for all days is 4%. He decides to test his hypothesis at the 5% level of significance. He randomly samples the manual records for Mondays and finds that, out of 150 weekly timesheets, 9 had absences on Mondays. (a) Is there sufficient evidence from the sample to confirm his suspicion that the absentee rate is higher on Mondays? (b) If in fact the true absentee rate was 4% for Mondays, calculate the probability that the sample absentee rate would be as large, or larger, than 9 out of 150? (i.e. find the p-value)2.Tina Dennis is the chief accountant for Meek Industries. She believes that the current cash-flow problems of Meek Industries are due to the slow collection of accounts receivable. Contrary to upper management’s claim, she believes that more than 60 per cent of the accounts are in arrears more than three months. sample of 200 accounts showed that 140 were more than three months old. (a) At the 1% level of significance, can she conclude that more than 60 percent of the accounts are in arrears more than 3 months? (b) What is the probability of having a sample proportion of .70 or higher when the true proportion is .60? (i.e. Calculate the p-value).3.A ketchup manufacturer is in the process of deciding whether to produce a new extra-spicy brand. The company’s marketing-research department used a national telephone survey of 6,000 households and found that the extra-spicy ketchup would be purchased by 335 of them. A much more extensive study made 2 years ago showed that 5% of the households would purchase the brand then. (a) At the 2% level of significance, should the company conclude that there is an increased interest in the extra-spicy flavour? (b) Change the significance level to 1.5%. Would you still conclude that there is an increased interest in the extra-spicy flavour at a 1.5% level of significance?(c) Calculate the p-value.4.Harper’s.A