86%(7)6 out of 7 people found this document helpful
This preview shows page 4 - 5 out of 5 pages.
16. Continuing the last question, what is the variance ofX?(a) 25/3(b) 10(c) 25(d) 100(e) none of the above17. LetZbe a standard normal random variable, Φ the standard normal cdf, andcan arbitrarypositive number. Which of the following expressions isfalse? (Hint: draw a picture.)18. LetZbe a standard normal random variable, Φ the standard normal cdf, andcan arbitrarypositive number. Which of the following quantities is larger than the others?4
19. LetXbe a normal random variable with mean 85 and standard deviation 10. Knowing thatΦ(1.5) = 0.9332, what is the probability thatX≥70?20. LetXbe the time (hours) between two successive arrivals at the drive-up window of a localbank. SupposeXfollows an exponential distribution withλ= 1; so the cdf ofXis given byF(x) =(0x <01-e-xx≥0Given that the last arrival occurred half an hour ago, what is the probability that no one elsewill arrive within the next half hour?(a)e-1(b) 1-e-1(c)e-1/2(d) 1-e-1/2(e) none of the above5