When we make inferences about ONE POPULATION PROPORTION, what assumptions do we need to make? Mark all that apply.

Data must be from a simple random sample.

Data is categorical.

Counts of successes and failures at least 15 each.

Data is categorical.

Counts of successes and failures at least 15 each.

The distribution of the amount of money in savings accounts for University of Alabama students has an average of 950 dollars and a standard deviation of 1,000 dollars. Suppose that we take a random sample of 4 University of Alabama students and ask them how much they have in their savings account. The sampling distribution of the sample mean amount of money in a savings account is

not approximately normal

If n is greater than 30 or if the original population is normally distributed, what is the approximate shape of the sampling distribution of the sample mean?

Normal

MARK ALL THAT ARE TRUE!! We can use the Normal (Z) table to find probabilities about:

You must choose all five correct statements to get credit.

averages based on small n, if the population is Normal

individuals, if the population is Normal

sample proportion of successes out of n independent trials, when np and n(1-p) is large enough

averages based on large n, if the population is Normal

averages based on large n, if the population is NOT Normal

individuals, if the population is Normal

sample proportion of successes out of n independent trials, when np and n(1-p) is large enough

averages based on large n, if the population is Normal

averages based on large n, if the population is NOT Normal

What is the standard error of the sampling distribution of the sample mean?

sigma/sqrt(n)

In 2006,the General Social Survey (which is conducted uses a method similar to simple random sampling) included a question that asked, “Do you see yourself as someone who is sociable?” For this question, 470 people said that they definitely did out of 1514 randomly selected people. What is the 95% confidence interval for the proportion of all Americans who believe that believe that they are sociable?

(0.2871, 0.3337)