AP Stats Unit 5

Let X be a random variable that has a skewed distribution with mean µ = 10 and standard deviation σ = 10. Based on random samples of size 400, the sampling distribution of X is

• highly skewed with mean 10 and standard deviation 10

• highly skewed with mean 10 and standard deviation 5

• highly skewed with mean 10 and standard deviation 0.5

• approximately normal with mean 10 and standard deviation 10

• approximately normal with mean 10 and standard deviation 0.5

The average cost for a gallon of gasoline is $2.51 (source AAA.org) with a standard deviation of $0.42. Find the mean and standard error of the sampling distribution if n = 49

• μ_x-bar = 2.51, σ_x-bar = 0.06

• μ_x-bar = 0.358, σ_x-bar = 0.06

• μ_x-bar = 2.51, σ_x-bar = 0.06

• μ_x-bar = 2.51, σ_x-bar = 0.857

Following a recent dramatic drop of 500 points in the Dow Jones Industrial Average, a poll conducted for the Associated Press found that 92% of those polled said that a year from now their family financial situation will be as good as it is today or better. Which of the following terms describes the number 92%?

• statistic

• sample

• sample parameter

• population parameter

• population

A distribution showing the sample means of all sample of size n of a population is called

• Normal Distribution

• Binomial Distribution

• Sampling Distribution

• Uniform Distribution

The mean and standard deviation of a population are 200 and 20, respectively. Sample size is 25. 
What is the standard deviation of the sampling distribution?

• 200

• 16

• 25

• 4

Calculate μ_x-bar and σ_x-bar if μ = 794, σ = 48, and n = 64

• μ_x-bar = 794, σ_x-bar = 0.75

• μ_x-bar = 12.4, σ_x-bar = 0.75

• μ_x-bar =794, σ_x-bar = 6

• μ_x-bar = 99.25, σ_x-bar = 6

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 400 children. What is the probability that at most 16% of children live in households with less than the official poverty level?

• 0.0003

• 0.0019

• 0.9968

• 0.9999

• 0

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

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 nq are both > 10

A realtor has been told that 43% of homeowners in a city prefer to have a finished basement. She surveys a group of 300 homeowners randomly chosen from her client list. Describe the sampling distribution model of the proportion of homeowners in this sample who prefer a finished basement.

• mean = 43%; standard deviation = 1.4%

• mean = 57%; standard deviation = 2.9%

• mean = 57%; standard deviation = 1.4%

• mean = 43%; standard deviation = 2.9%

• There is not enough information to describe the distribution.