Consider the set of sample data below. a. Compute the mean and standard deviation for these sample data. b. Calculate the coefficient of variation for these sample data and interpret its meaning. c. Using Tchebysheff's theorem, determine the range of values that should include at least 89% of the data. Count the number of data values that fall into this range and comment on whether your interval range was conservative or not. 80 124 142 82 111 101 60 120 132 90 76 136 86 123 D a. The mean is (Round to two decimal places as needed.)