This Question: 1 pt The shape of the distribution of the time required to get an oil change at a 20-minute of change facility is unknown. However, records indicate that the mean time is 21.5 minutes, and the standard deviation is 3.7 minutes. Complete parts (a)
through (c)
(a) To computo probabilities regarding the sample mean using the normal model, what size sample would be required?
O A The sample size needs to be less than or equal to 30.
OB. The normal model cannot be used if the shape of the distribution is unknown
OC. Any sample size could be used
OD. The sample size needs to be greater 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 20 minutes?
The probability is approximately
(Round to four decimal places as needed)
(c) Suppose the manager agrees to pay each employee a $50 bonus if they meet a certain goal. On a typical Saturday, the oil change facility will perform 35 oil changes between 10 AM, and 12 P. M. Treating this as a random sample, there
would be a 10% chance of the mean oil change time being at or below what valuo? This will be the goal ostablished by the manager
There is a 10% chance of being at or below a mean oi-change time of minutes.
Round to one decimal place as needed.)