The shape of the distribution of the time required to get an oil change at a 202

ID: 2947158 • Letter: T

Question

The shape of the distribution of the time required to get an oil change at a

2020?-minute

?oil-change facility is unknown.? However, records indicate that the mean time is

21.3 minutes21.3 minutes?,

and the standard deviation is

4.6 minutes4.6 minutes.

?(a) To compute probabilities regarding the sample mean using the normal? model, what size sample would be? required?

?(b) What is the probability that a random sample of

nequals=4040

oil changes results in a sample mean time less than

2020

?minutes?

a) We require at least sample size of 30

b) P(z<(20-21.3)/4.6)*SQRT(40)

= p(Z<-1.51)

= 0.0652

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