* For Questions (18)-(20): The grades in a general exam had mean 70 and standard deviation 5 and the range was 30. Let X be the grade of a student and assume that each grade X is changed to Y= - 2X +3, then (18) The mean 7 of the transformed grades Y is (a) -140 (b) 140 (c) 137 (d) -137 (19) The standard deviation of the transformed grades Y is (a) 5 (b) 10 (c)-10 (d) 13 (20) The range of the transformed grades Y is (a) 60 (b)-60 (c) 57 (d) 63 (21) The grades of Calculus I are bell-shaped (i.e. symmetric) with mean 65 and standard deviation 10. The proportion of grades between 55 and 85 is (a) 0.68 (b) 0.475 (c) 0.815 (d) 0.95 * For Questions (22)-(23): Suppose that the mean and standard deviation of a sample of 4 observations are 6 and 2, respectively. (22) If each observation is multiplied by -2 and then 5 is added to each observation, then the standard deviation becomes (a) 4 (b) 8 (c) 1 (d) -4 (23) The largest proportion of observations outside the interval [2, 10) (a) 0 (b) 0.25 (c) 0.75 (d) 1 * For Questions (24)-(25): The mean of a sample of 5 numbers is 4 and the standard deviation is 1. One number was changed from 4 to 6. (24) The new mean becomes (a) 6 (b) 5.4 (c) 4.4 (25) The new standard deviation becomes (a) 1.44 (b) 1.2 (c) 1.80 (d) 1.34 (d) 6.4