Il. Ture or false(2 points each). 1) A sample standard deviation is the square root of the sum of the squared differences around the mean devided by the sample size. 2) The coefficient of variation is especially usefull when comparing two or more sets of data that are measured in different units. 3) 4) Suppose, in testing a hypothesis about a mean, the p-value is computed to be 0.043. The null hypothesis should be rejected if the chosen level of significance is 0.05. 2) A statistics professor wanted to test whether the grades on a statistics test were the same for upper and lower classmen. The professor took a random sample of size 10 from each, conducted a test, and found out that the variances were equal. For this situation, the professor should use a f test with related samples. 3) A test for the difference between two proportions can be performed using the chi-square distribution. 4) The value of correlation coefficient (r) is always positive. 5) In a sample of size 40, the sample mean is 15. In this case, the sum of all observations in the sample is E Xi = 600