### Home > PC3 > Chapter 12 > Lesson 12.2.2 > Problem12-115

12-115.

A large urn contains $30$ black blocks and $10$ white blocks. A block is drawn from the urn four times and then replaced. What is the probability that exactly three of the four blocks drawn are white?

$P(\text{white block})=\frac{10}{40}$

$\Big(\begin{array}{c c}4\\3\end{array}\Big)\Big(\frac{10}{40}\Big)^3 \Big(\frac{30}{40}\Big)^1$