## anonymous 4 years ago Find the probability. A die is rolled 20 times and the number of twos that come up is tallied. Find the probability of getting exactly five twos. A. 0.129 B. 0.921 C. 0.003 D. 0.083

1. anonymous

binomial prob for this one $P(X=k)=\dbinom{n}{k}p^k(1-p)^{n-k}$ in your example $$n=20,k=5,p=\frac{1}{6},1-p=\frac{5}{6}$$

2. anonymous

your answer is therefore $\dbinom{20}{5}(\frac{1}{6})^5(\frac{5}{6})^{15}$

3. anonymous
4. anonymous