In Spring 2017, data was collected from a random selection of STA 2023 students. One of the questions asked how many hours they
1 answer:
Answer: 0.22
Step-by-step explanation:
We know that the best point estimate for the difference between two population mean is the difference between their sample means.
Given : For the 39 randomly selected upperclassmen, the sample mean was 0.12 and sample standard deviation was 0.42. For the 35 randomly selected underclassmen, the sample mean was 0.34 and the sample standard deviation was 0.87.
Let A denotes the population of upperclassmen and B denotes the population of underclassmen .
Then, the point estimate of the difference in the population mean volunteered between underclassmen and upperclassmen will be :-
Hence, the point estimate of the difference in the population mean volunteered between underclassmen and upperclassmen =0.22
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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;