The shape of the distribution of the time required to get an oil change at a 15 minute facility is unknown. However, records indicate that the mean time is 16.1 minutes and the standard deviation is 4.6 minutes.

a. To compute the 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 n = 40 oil changes results in a sample mean time of less than 15 minutes?

solution:

as, mean is defined as sum of all the observations divided by total number of observations.

and , median is mid value of the data whether arranged in ascending order or descending order.

consider, roadsters:

2,3,4,5,6,7,8,9

mean =

also, median= , because number of observations is even, so median is mean of two mid values.

now, coming to bandits

2,3,4,5,6

mean =  

median = 4, as number of observations is odd.

so, roadsters has greater median as well mean than bandits.

→option a is true about the repairs performed on 2 types of cars:

bandits have lower median and mean than roadsters.

(x+3)(x+7)

step-by-step explanation:

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step-by-step explanation:

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c. histogram

step-by-step explanation: