E270 HW3

# E270 HW3 - HOMEWORK PROBLEMS FOR CHAPTER 3 Use the z-table...

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HOMEWORK PROBLEMS FOR CHAPTER 3 Use the z-table to compute the fol owing SEVEN probabilities: 1 P(−1 ≤ z ≤ 0) a) 0.3695 b) 0.3413 c) 0.3144 d) 0.2876 2 P(−1.5 ≤ z ≤ 0) a) 0.3621 b) 0.3858 c) 0.4095 d) 0.4332 3 P(−2 < z < 0) a) 0.4061 b) 0.4298 c) 0.4535 d) 0.4772 4 P(−2.5 ≤ z ≤ 0) a) 0.4938 b) 0.4701 c) 0.4464 d) 0.4227 5 P(0 ≤ z ≤ 1.85) a) 0.5224 b) 0.4750 c) 0.4678 d) 0.4513 6 P(z > 0.75) a) 0.7734 b) 0.2266 c) 0.8121 d) 0.1879 7 P(z ≥ -0.38) a) 0.3520 b) 0.6480 c) 0.4801 d) 0.5199 8 a) 0.6536 b) 0.6826 c) 0.7034 d) 0.7245 Next THREE questions are based on the fol owing The random variable x is normal y distributed with a mean of 90 and a standard deviation of 20. 9 P(x < 85) = ______. a) 0.0912 b) 0.1587 c) 0.3694 d) 0.4013 10 P(x > 115) = ______. a) 0.1056 b) 0.1251 c) 0.8944 d) 0.8749 11 What proportion of x values fal within ±1.5 standard deviations from the mean? a) 0.7888 b) 0.8064 c) 0.8664 d) 0.9426 12 a) 0.8665 b) 0.8869 c) 0.1335 d) 0.1131 Next TWO questions are based on the fol owing 13 What fraction of commuting times are within 15 minutes of the mean commuting time? a)

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E270 HW3 - HOMEWORK PROBLEMS FOR CHAPTER 3 Use the z-table...

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