Introduction to the Practice of Statistics 9th edition by David S. Moore Test bank

 A)0.048
 B)0.452
 C)0.711
 D)0.952
 
 
211.A market research company employs a large number of typists to enter data into a computer database. The time it takes for potential new typists to learn the computer system is known to have a Normal distribution with a mean of 90 minutes and a standard deviation of 18 minutes. A candidate is automatically hired if she learns the computer system in less than 100 minutes. A cut-off time is set at the slowest 10% of the learning distribution. Anyone slower than this cut-off time is definitely not hired.
What proportion of candidates will be hired automatically?
 A)0.048
 B)0.452
 C)0.711
 D)0.952
 
 
212.A market research company employs a large number of typists to enter data into a computer database. The time it takes for potential new typists to learn the computer system is known to have a Normal distribution with a mean of 90 minutes and a standard deviation of 18 minutes. A candidate is automatically hired if she learns the computer system in less than 100 minutes. A cut-off time is set at the slowest 10% of the learning distribution. Anyone slower than this cut-off time is definitely not hired.
What is the cut-off time the market research company uses?
 A)1 hour and 7 minutes
 B)1 hour and 53 minutes
 C)2 hours
 D)2 hours and 8 minutes
 
 
213.Which of the following statements about the standardized z-score of a value of a variable X, which has a mean of m and a standard deviation of s, is/are TRUE?
 A)The z-score has a mean equal to 0.
 B)The z-score has a standard deviation equal to 1.
 C)The z-score tells us how many standard deviation units from the original observation fall away from the mean.
 D)The z-score tells us the direction the observation falls away from the mean.
 E)All of the above statements about the z-score are true.
 
 
214.A well-known maker of jams and jellies packages its jams in jars labeled “250 milliliters.” The process used to fill the jars is known to dispense an amount of jam that is a Normally distributed variable with m = 252 milliliters and s = 0.9 milliliters. What proportion of the jars filled by the process will contain less than 250 milliliters?
 A)0.5
 B)0.9868
 C)0.0068
 D)0.0131
 E)0
 
 
215.A well-known maker of jams and jellies packages its jams in jars labeled “250 milliliters.” The process used to fill the jars is known to dispense an amount of jam that is a Normally distributed variable with m = 252 milliliters and s = 0.9 milliliters. What proportion of jars from this filling process will contain no more than 253.5 milliliters?
 A)0.9678
 B)0.9522
 C)0.9973
 D)0.0027
 E)0.0475
 
 
216.A well-known maker of jams and jellies packages its jams in jars labeled “250 milliliters.” The process used to fill the jars is known to dispense an amount of jam that is a Normally distributed variable with m = 252 milliliters and s = 0.9 milliliters. What percentage of jars will be filled with between 251 milliliters and 254 milliliters?
 A)85.3%
 B)1.3%
 C)14.7%
 D)13.4%
 E)8.5%
 
 
217.A well-known maker of jams and jellies packages its jams in jars labeled “250 milliliters.” The process used to fill the jars is known to dispense an amount of jam that is a Normally distributed variable with m = 252 milliliters and s = 0.9 milliliters. What proportion of jars will be filled with what the label claims is 250 milliliters?
 A)0.9868
 B)0
 C)0.0068
 D)0.0132
 E)0.0027
 
 
218.A well-known maker of jams and jellies packages its jams in jars labeled “250 milliliters.” The process used to fill the jars is known to dispense an amount of jam that is a Normally distributed variable with m = 252 milliliters and s = 0.9 milliliters. If changing s while keeping m the same were possible for this process, what should s be set at so that the percentage of jars filled with less than 250 milliliters will be at most 0.2%?
 A)s = 2.38
 B)s = 1
 C)s = 0.69
 D)s = 0.82
 E)It should not be within ± 0.2 of any of the above.
 
 
219.A tool and die company has been contracted to produce metal castings into which a hole is to be drilled to a diameter of 2.5 centimeters. Because of the variability in the drilling process, the actual diameter of the hole is a Normally distributed variable with a mean of 2.5 centimeters and a standard deviation of 0.1 centimeters. The proportion of castings produced by this process with a hole whose diameter is within 0.2 centimeters of the desired value is