Because not all airline passengers show up for their reserved seat, an airline sells 75 tickets for a flight that holds only 72 passengers. The probability that a passenger does not show up is 0.10, and the passengers behave independently. What is the probability that more than 72 passengers will show up? What are the mean and standard deviation of the number of passengers who show up?

Question

mathmagician · Answer

prob that there will be exactly 73 people, is $$C _{75}^{73}*0.9^{73}*0.1^{2}=0.0127$$

mathmagician · Answer

Prob, that there will be 74 people, is $$C _{75}^{74}*0.9^{74}*0.1=0.003$$
Prob, that there will be 75 people, is 0.00037. Finally, prob that there will be more than 72 people, is 0.01607

anonymous · Answer

is C=n!/ x!(n-x)! ?

mathmagician · Answer

yes

anonymous · Answer

okay great! what did you get get for the mean and std? i just wanna check my answers