The shape of the distribution of the time required to get an oil change at a 10-minute oil-change facility is unknown. However, records indicate that the mean time for an oil change is 11.4 minutes, and the standard deviation for oil-change time is 3.2 minutes. a.) To compute probabilities regarding the sample mean using the normal model, what size would be required? b.) What is the probability that a random sample of 40 oil changes will result in a sample mean time of less than 10 minutes? Would this be considered unusual? Draw a graph that represents the probability. c.) What is the probability that a random sample of 40 oil-changes will result in a sample mean time of 11 to 14 minutes? Draw a graph that represents this probability. d.) What is the probability that a random sample of 40 oil-changes will result in a sample mean greater than 12 minutes? Draw a graph that represents this probability.
The shape of the distribution of the time required to get an oil change at a 10-minute oil-change
facility is unknown. However, records indicate that the mean time for an oil change is 11.4 minutes, and
the standard deviation for oil-change time is 3.2 minutes.
a.) To compute probabilities regarding the sample mean using the normal model, what size
would be required?
b.) What is the
time of less than 10 minutes? Would this be considered unusual? Draw a graph that represents
the probability.
c.) What is the probability that a random sample of 40 oil-changes will result in a sample mean
time of 11 to 14 minutes? Draw a graph that represents this probability.
d.) What is the probability that a random sample of 40 oil-changes will result in a sample mean
greater than 12 minutes? Draw a graph that represents this probability.
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