Sampling Distribution on Mean and Proportion

Your mail-order company advertises that it ships 90% of its orders within three working days. You select an SRS of 100 of the 5000 orders received in the past week for an audit.<\/p>

What symbol would you use for the mean of the sample?<\/p>

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Answer explanation

The Central Limit Theorem kicks in here since the sample size is greater than 30. The sampling distribution would be skewed right for samples less than 30

The amount of fuel used by jumbo jets to take off is normally distributed with a mean of 4000 gallons and a standard deviation of 125 gallons. What is the shape, mean and standard deviation of the distribution of sample means from samples of size n = 81. This would be a problem dealing with...

• Proportions

• Means

Suppose the teenagers that attend public high schools get an average of 5.7 hours of sleep each night with a standard deviation of 1.7 hours. The distribution of sleep time is skewed to the left. What is the shape, mean, and standard deviation of the distribution of sample means from samples of size n = 400? This is a ____ question.

• Proportions

• Means

These symbols represent the mean and standard deviation for which of the following distributions?

• The Population

• The Sample

• The Sampling Distribution

28% of all Woodrow students believe Monday will be snow day. You take a sample of 50 students and find that 15 of them believe Monday will be a snow day. What symbol would we use to represent 15?

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According to the Center for Disease Control, 93% of children entering kindergarten in the U.S. are vaccinated. A school district has 180 incoming kindergarten children.

Which of the following is true concerning the shape of the sampling distribution?

• The sampling distribution is normal because n > 30

• The sampling distribution is not normal because nq is < 30

• The sampling distribution is normal because 93% of 180 is > 10

• The sampling distribution is normal because np and n(1-p) are both > 10

Researchers found that boys playing high school football absorb an average of 355 hits to the head with a standard deviation of 80 hits during a season. If samples of 48 high school football players are randomly selected, what type of formulas would you use?

• Proportions

• Means

What happens to the shape of a sampling distribution of sample means as n increases?

• The skew gets bigger

• The skew is reversed

• It becomes narrower and more normal.

• The shape is the same, but wider

What is the mean of the sampling distribution?

• 400

• 40

• 25

• 8