Sampling Proportions and Means

The Gallup Poll asked a random sample of 1785 adults whether they attended church during the past week.  We will count the number of people in the sample who attended church.  A newspaper report claims that 40% of all U.S. adults went to church last week.  What type of analysis would we do?

• Proportion

• Means

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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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

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

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

• The Population

• The Sample

• The Sampling Distribution

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

According to government data, 22% of American children under the age of six live in households with incomes less than the official poverty level. A study of learning in early childhood chooses an SRS of 300 children. Are the conditions/assumptions for normality met?

• Yes, all of them are met.

• No, the sample is not random

• No, we have less than 10 successes

• No, 300 is more than 10% of all children

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

• The Population

• The Sample

• The Sampling Distribution