Question 18 (1 point) The value of the sum of the deviations from the mean, i.e., ( _ _ must always be (look carefully at the sum term). negative. either positive or negative, depending on whether the mean is positive or negative. zero. less than zero.Question 13 (1 point) If P(A) - 0.7, P(B) = 0.6, P(An B) - 0, then events A and B are independent events. supplementary events. complements of each other. mutually exclusive.Question 17 (1 point) The numbers of hours worked (per week) by 400 statistics students are shown below. Number of hours Frequency 0 -9 20 10 - 19 80 20 - 29 200 30 - 39 100 What percentage of the students worked 29 hours or less? O 25% O 50% 75% 100%