Question 1075656: A box contains six tickets, with letters: A, B, C, D, D, E. Note that there are 2 D’s in the box. Nine draws will be made at random with replacement. Find the probability that exactly four of the tickets drawn will be a D. Express your answer as a percent.
9 C 4 (2/6)^4 (4/6)^5 I am right so far... nobody replied yesterday...
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! p(d) = 2/6 = 1/3
binomial probability is used with p = 1/3 and q = 1 - p = 2/3
binomial probability formula is p(x) = p^x * q^(n-x) * c(n,x)
this becomes p(4) = (1/3)^4 * (2/3)^5 * c(9,4)
that looks like what you have.
when you evaluate it, you get p(4) = .2048468221.
from what i know, i believe you are correct.
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