SOLUTION: An accounting firm in a college town usually recruits employees from two of the universities in town. This year, there are fifteen graduates from University A and five from Univers

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Question 622112: An accounting firm in a college town usually recruits employees from two of the universities in town. This year, there are fifteen graduates from University A and five from University B and the firm decides to hire six new employees from the two universities. What is the probability that at least one of the new employees will be from University B?
Answer by solver91311(24713) About Me  (Show Source):
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The probability of successes in trials where is the probability of success on any given trial is given by:



Where is the number of combinations of things taken at a time and is calculated by

You need the probability of 1 plus the probability of 2 plus ... and so on up to and including the probability of 6.



Which is a bunch of nasty arithmetic. Easier is to recognize that "at least 1" is all of the outcomes except 0, so you can get your answer from:

.

Also note that there are 15 A students and 5 B students, so there are 20 students all together, hence the probability of a B student on any individual trial is . Do the indicated arithmetic.

John

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