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- - **This is simple for you, hard for me...**
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This is simple for you, hard for me....I really need to know how to do a question like this for a course I am taking. Can you help????
Out of 2 million hay fever sufferers in Canada, 82% are allergic to ragweed. If a random sample of 7 hay fever sufferers is selected, a) what is the probability that 3 are allergic to ragweed? b) What is the probability that 1 is allergic to ragweed? What is the formula??? |

The basic idea is to use the binomial distribution with p=.82 and q=.18.
That is expand (p+q) ^{n} into powers of p (and q). Then the probability of exactly k yesses is {n,k}p ^{k}q^{n-k}. I am using {n,k} to represent n!/k!(n-k)!. In your problem, n=7 and k=1 or k=3. |

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