A pair of dice thrown independently 3 times.

Question

A pair of dice thrown independently 3 times. Find the probability of getting a sum of 9 exactly twice.

Accepted Answer

$P(\text{sum}=9)=\dfrac{4}{36}=\dfrac19$.

$$P = {}^3C_2\left(\frac19\right)^2\left(\frac89\right) = \frac{8}{243}$$

Solutions · 1