Showing 21 to 30 of 426 Questions
  • A group of Florida State University psychologists examined the effects of alcohol on the reactions of people to a threat (Journal of Abnormal Psychology, Vol. 107, 1998). After obtaining a specified blood alcohol level, the psychologists placed experimental subjects in a room and threatened them with electric shocks. Using sophisticated e

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  • A high-volume printer produces minor print-quality errors on a test pattern of 1000 pages of text according to a Poisson distribution with a mean of 0.4 per page.(a) Why is the number of errors on each page independent random variables?(b) What is the mean number of pages with errors (one or more)?(c) Approximate the probability that more

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  • A machine is used to cut a metal automobile part to its desired length. The machine can be set so that the mean length of the part will be any value that is desired. The standard deviation of the lengths always runs at .02 inch. Where should the mean be set if we want only .4 percent of the parts cut by the machine to be shorter than 15 i

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  • A motel accepts 325 reservations for 300 rooms on July 1, expecting 10 percent no- shows on average from past records. Use the normal approximation to the binomial to find the probability that all guests who arrive on July 1 will receive a room.

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  • A multiple choice exam is given. A problem has four possible answers, and exactly one answer is correct. The student is allowed to choose a subset of the four possible answers as his answer. If his chosen subset contains the correct answer, the student receives three points, but he loses one point for each wrong answer in his chosen subse

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  • A number is chosen at random from the integers 1, 2, 3, . . . , n. Let X be the number chosen. Show that E(X) = (n+1)/2 and V (X) = (n−1)(n+1)/12. Hint: The following identity may be useful:

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    197
  • A physical-fitness association is including the mile run in its secondary-school fitness test for students. The time for this event is approximately normally distributed with a mean of 450 seconds and a standard deviation of 40 seconds. If the association wants to designate the fastest 10% of secondary-school students as “excellent,”

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  • A privately owned liquor store operates both a drive-in facility and a walk-in facility. On a randomly selected day, let A" and Y, respectively, be the proportions of the time that the drive-in and walk-in facilities are in use, and suppose that the joint density function of these random variables is(a) Find the marginal density of X.(b)

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    193
  • A process is said to be of six-sigma quality if the process mean is at least six standard deviations from the nearest specification. Assume a normally distributed measurement.(a) If a process mean is centered between the upper and lower specifications at a distance of six standard deviations from each, what is the probability that a produ

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  • A random variable X has the discrete uniform distribution show that the moment-generating function of Xis

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