De_thi_thu_mon_MAS201-FB601

# De_thi_thu_mon_MAS201-FB601 - thi th mn MAS201 1 If the...

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1) If the time it takes for a customer to be served at a fast-food chain business is thought to be uniformly distributed between 3 and 8 minutes, what is the probability that the time it takes for a randomly selected customer will be less than 5 minutes? A) 0.30 B) 0.80 C) 0.40 D) 0.20 2) The manager of a computer help desk operation has collected enough data to conclude that the distribution of time per call is normally distributed with a mean equal to 8.21 minutes and a standard deviation of 2.14 minutes. The manager has decided to have a signal system attached to the phone so that after a certain period of time, a sound will occur on her employees' phone if she exceeds the time limit. The manager wants to set the time limit at a level such that it will sound on only 8 percent of all calls. Let P(Z < 1.41) = 0.92, P(Z < -1.41) = 0.08, the time limit should be: A) approximately 5.19 minutes B) about 14.58 minutes. C) 10.35 minutes. D) about 11.23 minutes. 3) The monthly electrical utility bills of all customers for the Far East Power and Light Company are known to be distributed as a normal distribution with mean equal to \$87 a month and standard deviation of \$36. If a statistical sample of n = 100 customers is selected at random, what is the probability that the mean bill for those sampled will exceed \$75? Let P(Z < -3.33) = 0, P(Z < 0.33) = 0.63 and P(Z < -0.44) = 0.33. A) 0.33 B) Approximately 0.63 C) About 1.00 D) None of the others. 4) In an application to estimate the mean number of miles that downtown employees commute to work roundtrip each day, the following information is given: n = 20; = 4.33; s = 3.50. The point estimate for the true population mean is: A). 1.638. B) 4.33 C) 4.33 ± 1.638. D) None of the above. 5) A major tire manufacturer wishes to estimate the mean tread life in miles for one of their tires. They wish to develop a confidence interval estimate that would have a maximum sampling error of 500 miles with 90 percent confidence. Let population standard deviation equal to 4,000 miles. Based on this information and let z 0.05 = 1.645, the required sample size is: A) 196. B) 124. C) 246. D) 174. 6) Given = 15.3, s = 4.7, and n = 18, form a 99% confidence interval for σ 2 . Let A) (13.61, 43.30) B) (10.51, 65.88) C) (2.24, 14.02) D) (11.13, 69.79) 7) In an application to estimate the mean number of miles that downtown employees commute to work roundtrip each day, the following information is given: n = 20; = 4.33; s = 3.50. Based on this information and let t 0.025,19 = 2.09, the upper limit for a 95 percent confidence interval estimate for the true population mean is: A) about 5.97 miles. B) nearly 12.0 miles. C) about 7.83 miles.

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## This note was uploaded on 03/20/2012 for the course STAT 101 taught by Professor Kelly during the Two '12 term at Royal Melbourne Institute of Technology.

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De_thi_thu_mon_MAS201-FB601 - thi th mn MAS201 1 If the...

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