A class is made out of 22 students, The sample mean is 26.91, and the sample st. dev is 10.46. ? a= 0.05  Gender F F M F F F M F M F F M F F F M F M F M M F Age 39 19 17 44 33 22 48 21 29 28 28 21 54 19 18 23 21 21 19 23 18 27 Claim: the proportion of males in online classes is 35%. Can you prove it is not? o What is the null hypothesis? o What is the alternative hypothesis? o What distribution should be used? o What is the test statistic? o What is the p-value? o What is the conclusion? o How do we interpret the results, in context of our study?

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 + ...