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According to an airline, a particular flight is on time 91% of the time. Suppose 49...

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cbromm | Honors

Posted July 3, 2013 at 2:22 AM via web

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According to an airline, a particular flight is on time 91% of the time. Suppose 49 flights are randomly selected and the number of on time flights is recorded. What is the probability that between 42 and 44 flights, inclusive are on time?

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted July 3, 2013 at 2:47 AM (Answer #1)

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A particular flight is on time 91% of the time. The probability that it is on time is 0.91 and the probability that is not time is 0.09.

49 flights are randomly selected and the number of on time flights is recorded. The probability that 42, 43 or 44 flights are on time is:

`C(49, 42)*0.91^42*0.09^7` + `C(49, 43)*0.91^43*0.09^6` + `C(49, 44)*0.91^44*0.09^5`

`~~ 0.3845`

There is a approximate probability of 0.3845 that of the 49 flights 42, 43 or 44 flights are on time.

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