







A binomial probability problem 
20080108 

From rougi: According to statistics of the company about 4% of the people who buy tickets do not arrive to the flight . The company sells 205 tickets to plane that has 200 places . Use the binomial distribution to calculate what is the probability that all the people who come to the flight get a place. Answered by Harley Weston. 





Colour blindness 
20070329 

From Katrina: 9% of men and .25% of woman can't distinguish between
the colors red and green. This is the type of color blindness
that causes problems with traffic lights. If 6 men are randomly
selected for a study of traffic signal perceptions, find the probability
that exactly two of them cannot distinguish between red and green. Answered by Stephen La Rocque. 





Three keys 
19981126 

From Karen Chan: A man has a bunch of three keys, only one of which fits the lock of his front door. When he comes home in the dark he tries the keys at random until he finds the one fits. Find the probability that in a week of five nights, he tries the right key first on at least one night. Answered by Penny Nom. 

