Question

Let x be a discrete random variable. if pr(x<9) = 1/6, and pr(x>9) = 1/3, then what is pr(x=9)?

Answer 1

Answer: 1/2

Step-by-step explanation:

The probabilities must add to 1, so:

$P(x < 9) +P(X=9)+P(X > 9)=1\\\\\frac{1}{6}+P(X=9)+\frac{1}{3}=1\\\\P(X=9)=\boxed{\frac{1}{2}}$