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21. The fracture strength of tempered glass averages 14 (measured in thousands of pounds per square inch) and has a standard deviation of 2. What is the probability that the average fracture strength of 100 randomly selected pieces of this glass exceeds 14.5? 22. Workers employed in a large service industry have an average wage of $7.00 per hour with a standard deviation of $0.50. The industry has 64 workers of a certain ethnic group. These workers have an average wage of $6.90 per hour. Is it reasonable to assume that the wage rate of the ethnic group is equivalent to that of a random sample of workers from those employed in the service industry? [Hint: Calculate the probability of obtaining a sample mean less than or equal to $6.90 per hour.] 23. Shear strength measurements for spot welds have been found to have a standard deviation of 10 pounds per square inch (psi). If 100 test welds are to be measured, what is the approximate probability that the sample mean will be within psi of the true population mean?

          21. The fracture strength of tempered glass averages 14 (measured in thousands of pounds per square inch) and has a standard deviation of 2. What is the probability that the average fracture strength of 100 randomly selected pieces of this glass exceeds 14.5? 

22. Workers employed in a large service industry have an average wage of $7.00 per hour with a standard deviation of $0.50. The industry has 64 workers of a certain ethnic group. These workers have an average wage of $6.90 per hour. Is it reasonable to assume that the wage rate of the ethnic group is equivalent to that of a random sample of workers from those employed in the service industry? [Hint: Calculate the probability of obtaining a sample mean less than or equal to $6.90 per hour.]

23. Shear strength measurements for spot welds have been found to have a standard deviation of 10 pounds per square inch (psi). If 100 test welds are to be measured, what is the approximate probability that the sample mean will be within psi of the true population mean?

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