Question 205374: To use telephone banking to paybills,the customerhas to enter the last three digits of each bill. The numbers 0 to 9 inclusive can be used. If the numbers happen to be the same on more then one bill, the costumer has to enter the first 3 digits as well.
A.) What is the probability that a person has 2 bills to register with the same last 3 digits?
B.)What is the probability that a person with 10 bills to register has at least 2 bills with the same last 3 digits?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! If the numbers happen to be the same on more then one bill, the costumer has to enter the first 3 digits as well.
A.) What is the probability that a person has 2 bills to register with the same last 3 digits?
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P(a single digit from one bill is the same as a single digit from the other)
= (1/10)
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P(last thee from one are the same) = (1/10)^3 = 1/1000
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B.)What is the probability that a person with 10 bills to register has at least 2 bills with the same last 3 digits?
P(at least 2 of 10) = 1 - P(0<=x<=1) = 1 - binomcdf(10,1/10,1) = 0.2639
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I used a TI calculator to find binomcdf(10,1/10,1)
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Cheers,
Stan H.
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