MATH10120 Midterm: Math10120F14 Exam Solutions EX3_3_4_5
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Find the variance, 2, of x . k. We must rst nd the mean, e (x ) = = p kp(x = k) (d) From above, or by symmetry, we see = 4. 1/2 by symmetry, we see = 4. Next we must calculate 2 = e (x )2 = p(k )2p(x = k). 3 mr. drillit, the dentist of tooth acres, has determined from his records the probability distribution of the variable x = the number of llings he administers in a day. The probability distribution for the random variable x is given below. Find the variance, 2, of x . (a) q 5 (e) q 7 (d) (c) = 4 (k )2 ( 2)2 = 4 ( 1)2 = 1. 2 = 5/4 by symmetry, we see = 2. We must rst nd the mean, e (x ) = = p kp(x = k).
