In this case, we have $p=0.4$, $n=20$, and we want to find $P(X=9)$. Plugging these values into the formula, we get:
$P(X=9) = \binom{20}{9} \cdot 0.4^9 \cdot (1-0.4)^{20-9}$
Using a calculator or software, we can calculate this probability to be approximately
Show more…