Question 351702: There are five chemistry instructors and six physics instructors at a college. If a committee of four instructors is selected, find the probability that at least one of them is a physics instructor. Express your answer as a fraction in lowest terms.
I keep trying to multiply 5/11^4 and then subtracting from one and I cant get the answer. I am so confused.
Also, this problem:If three cards are drawn from a deck and not replaced, find the probability of getting at least one spade. Express your answer as a fraction in lowest terms.
I tried multiplying 39/52^3 and then subtracting from 1 but thats not it either and I have to have both of these in fraction form.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! There are five chemistry instructors and six physics instructors at a college. If a committee of four instructors is selected, find the probability that at least one of them is a physics instructor. Express your answer as a fraction in lowest terms.
I keep trying to multiply 5/11^4 and then subtracting from one and I cant get the answer. I am so confused.
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P(at least one physics) = 1 - P(no physics)
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= 1 - 5C4/11C4
= 1 - 0.0152
= 0.9848
= 1231/1250
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Also, this problem:If three cards are drawn from a deck and not replaced, find the probability of getting at least one spade. Express your answer as a fraction in lowest terms.
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P(at least one spade in three) = 1 - P(no spades in three)
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= 1 - 39C3/52C3
= 1 - 0.4135
= 0.5865
= 997/1700
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Cheers,
Stan H.
I tried multiplying 39/52^3 and then subtracting from 1 but thats not it either and I have to have both of these in fraction form.
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