The shape of the distribution of the time required to get an oil change at a 15-minute oil-change facility is unknown. However, records indicate that the mean time is 16.5 minutes, and the...

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

15-minute

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

16.5 minutes,

and the standard deviation is

4.2 minutes.

Complete parts (a) through

(c).

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

The normal model cannot be used if the shape of the distribution is unknown.

Any sample size could be used.

The sample size needs to be greater than or equal to 30.

Your answer is correct.

The sample size needs to be less than or equal to 30.

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

n=35

oil changes results in a sample mean time less than

minutes?

The probability is approximately

enter your response here.

(Round to four decimal places as needed.)

Jun 01, 2022

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