The U.S. Census Bureau reported that in 2015 the proportion of adult Americans, ages 25 and older, who have a bachelor's degree or higher is 0.325.† Consider the population of all adult Americans, ages 25 and over, in 2015 and define p̂ to be the proportion of people in a random sample from this population who have a bachelor's degree or higher. (a) Would p̂ based on a random sample of only 10 people from this population have a sampling distribution that is approximately normal? Explain why or why not.      , the sampling distribution of p̂ based on a random sample of size 10 residents would not be  approximately normally distributed because np is less than  10. (b) What are the mean and standard deviation of the sampling distribution of p̂ if the sample size is 200? (Round your standard deviation to four decimal places.) meanstandard deviation (c) Suppose that the sample size is  n = 100  rather than  n = 200.  What are the values for the mean and standard deviation when  n = 100?  (Round your standard deviation to four decimal places.) meanstandard deviation Does the change in sample size affect the mean and standard deviation of the sampling distribution of p̂? If not, explain why not. (Select all that apply.) When the sample size decreases, the mean increases.When the sample size decreases, the mean decreases.When the sample size decreases, the mean stays the same. The sampling distribution is always centered at the population mean, regardless of sample size.When the sample size decreases, the standard deviation increases.When the sample size decreases, the standard deviation decreases.When the sample size decreases, the standard deviation stays the same. The standard deviation of the sampling distribution is always the same as the standard deviation of the population distribution, regardless of sample size.

Definition Definition Measure of central tendency that is the average of a given data set. The mean value is evaluated as the quotient of the sum of all observations by the sample size. The mean, in contrast to a median, is affected by extreme values. Very large or very small values can distract the mean from the center of the data. Arithmetic mean: The most common type of mean is the arithmetic mean. It is evaluated using the formula: μ = 1 N ∑ i = 1 N x i Other types of means are the geometric mean, logarithmic mean, and harmonic mean. Geometric mean: The nth root of the product of n observations from a data set is defined as the geometric mean of the set: G = x 1 x 2 ... x n n Logarithmic mean: The difference of the natural logarithms of the two numbers, divided by the difference between the numbers is the logarithmic mean of the two numbers. The logarithmic mean is used particularly in heat transfer and mass transfer. ln x 2 − ln x 1 x 2 − x 1 Harmonic mean: The inverse of the arithmetic mean of the inverses of all the numbers in a data set is the harmonic mean of the data. 1 1 x 1 + 1 x 2 + ...