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2 answers:
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Answer:
Let X the random variable that represent the delivery times of a population, and for this case we know the distribution for X is given by:
Where and
Since the distribution of X is normal then we know that the distribution for the sample mean is given by:
And we have;
Step-by-step explanation:
Assuming this question: The delivery times for all food orders at a fast-food restaurant during the lunch hour are normally distributed with a mean of 14.7 minutes and a standard deviation of 3.7 minutes. Let R be the mean delivery time for a random sample of 40 orders at this restaurant. Calculate the mean and standard deviation of Round your answers to two decimal places.
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the delivery times of a population, and for this case we know the distribution for X is given by:
Where and
Since the distribution of X is normal then we know that the distribution for the sample mean is given by:
And we have;