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An airline has sold 560 tickets for a certain flight (with capacity 555 seats) in the assumption that not all passengers that purchased a ticket will arrive for the flight. Assume that the probability that a passenger will not show up for the flight is 1%, independently of all other passengers. How likely is it that there are more passengers showing up for the flight than seats are available? Calculate this probability by using a binomial distribution for the number of passengers that showed up for the flight.

User Emagar
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Answer:

There is a 34.09% probability that there are more passengers showing up for the flight than seats are available.

Explanation:

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.


P(X = x) = C_(n,x).\pi^(x).(1-\pi)^(n-x)

In which
C_(n,x) is the number of different combinatios of x objects from a set of n elements, given by the following formula.


C_(n,x) = (n!)/(x!(n-x)!)

And
\pi is the probability of X happening.

For this problem,

There are 560 tickets, so
n = 560

There is a 1% probability that a passenger will not show up for the flight, so
\pi = 0.01

How likely is it that there are more passengers showing up for the flight than seats are available?

An airline has sold 560 tickets for a certain flight (with capacity 555 seats).

So, this question is: What is the probability that at most 4 passengers do not show up for the flight.


P = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4)


P(X = x) = C_(n,x).\pi^(x).(1-\pi)^(n-x)


P(X = 0) = C_(560,0).(0.01)^(0).(0.99)^(560) = 0.0036


P(X = 1) = C_(560,1).(0.01)^(1).(0.99)^(559) = 0.0203


P(X = 2) = C_(560,2).(0.01)^(2).(0.99)^(558) = 0.0574


P(X = 3) = C_(560,3).(0.01)^(3).(0.99)^(557) = 0.1079


P(X = 3) = C_(560,4).(0.01)^(4).(0.99)^(556) = 0.1517

So


P = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4) = 0.0036 + 0.0203 + 0.0574 + 0.1079 + 0.1517 = 0.3409

There is a 34.09% probability that there are more passengers showing up for the flight than seats are available.

User Clementine
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