USA Today reported that about 20% of all people in the United States are illiterate. Suppose you take eleven people at random off a city street.   (a) Find the mean and standard deviation of this probability distribution. (Round your answers to two decimal places.) ? = ___people ? = ___ people Find the expected number of people in this sample who are illiterate. (Round your answer to two decimal places.) __people (b) How many people would you need to interview to be 94% sure that at least seven of these people can read and write (are not illiterate)? (Enter the smallest number of people needed to be at least 94% sure.) __people

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 + ...