Answer the following using the steps in hypothesis testing: (10 points each)

1. John Walker, the manager of MPV Industries, believes that the average daily wages of the company's employees are below 450. A sample of 22 employees has a mean daily wage of 418. The standard deviation of all salaries is 35. At = 0.01, is there enough evidence to support the manager's claim?

2. A clothing store believes that the mean income of the store's customers exceeds 30,000 per month. One hundred fifty customers are randomly selected and asked of their annual income. The sample mean is 30,500 and its standard deviation is 4,200. Is there sufficient evidence to indicate that the mean household income of the customers of the store exceeds 30,000 per month. Use = 0.05.

3. A study is conducted to compare the total printing time in seconds of two brands of laser printers on various tasks. Test at 0.05 if there is a difference in the printing time of the two brands.

Brand A Brand B

21.8 25.1

22.6 20.9

20.0 19.5

19.7 24.8

18.9 22.1

21.3 25.2

23.1 23.8

24.0 28.5