An article reported that what airline passengers like to do most on long flights
ID: 3020136 • Letter: A
Question
An article reported that what airline passengers like to do most on long flights is rest or sleep; in a survey of 3697 passengers, almost 90% did so. Suppose that for a particular route the actual percentage is exactly 90%, and consider randomly selecting six passengers. Then x, the number among the selected six who rested or slept, is a binomial random variable with n = 6 and p = 0.9. (Round your answers to four decimal places.)
(a) Calculate p(4). p(4) = Interpret this probability. This is the probability that at least 4 out of 10 selected passengers rested or slept. This is the probability that exactly 4 out of 6 selected passengers rested or slept. This is the probability that exactly 4 out of 10 selected passengers rested or slept. This is the probability that at least 4 out of 6 selected passengers rested or slept.
(b) Calculate p(6), the probability that all six selected passengers rested or slept. p(6) =
(c) Determine P(x 4). P(x 4) =
Explanation / Answer
This is the probability that exactly 4 out of 6 selected passengers rested or slept.
P(x=4 ) = 6C4 * 0.90^4 * 0.10^(6-4) = 0.098415
P( x = 6) = 6C6 * 0.90^6 * 0.10 ^[6-6] = 0.531441
P( x >= 4 ) = P( x=4) + P(x=5) + P(X=6)
P(x=5) = 6C5 * 0.90^5 * 0.10 ^[6-5] = 0.354294
P( x >= 4 ) =0.098415 + 0.354294 + 0.531441 = 0.98415
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