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These look simple, don't they!!!!

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These look simple, don't they!!!!

by hk » Fri Jun 12, 2009 7:19 pm
The probability that a guest at a party eats a pack of candy is 30%. If three guests come to the party, what is the probability that exactly two guests will eat a pack of candy?

a) 0.343
b) 0.147
c) 0.189
d) 0.063
c) 0.027
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by bluementor » Sat Jun 13, 2009 1:55 am
Three guest: A, B and C

P(exactly 2 guest eat candy) = P(A and B eat candy, C does not) OR P(A and C eat candy, B does not) OR P(B and C eat candy, A does not)

P(A and B eat candy, C does not) = (0.3)(0.3)(0.7)
P(B and C eat candy, A does not) = (0.7)(0.3)(0.3)
P(A and C eat candy, B does not) = (0.3)(0.7)(0.3)

So,


P(exactly 2 guest eat candy) = 3 x (0.3)(0.3)(0.7) = 3 x 0.063 = 0.189

Choose C.

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