Practicing Success
If a random variable X has the following probability distribution values of X.
Then, P( X ≥ 6)= |
$\frac{19}{100}$ $\frac{81}{100}$ $\frac{9}{100}$ $\frac{91}{100}$ |
$\frac{19}{100}$ |
Since the sum of the probabilities in a probability distribution is always unity. $∴ P(X=0)+P(X=1)+.....+P(X=7)=1$ $⇒ 0 + k + 2k + 2k + 3k + k^2 + 2k^2 + 7k^2 +k =1 $ $⇒ 10k^2 + 9k - 1=0 $ $⇒ (10k -1) (k+1)=0$ $⇒ 10k - 1= 0 $ $[∵k ≥ 0 ∴ k + 1 ≠ 0]$ $⇒ k = \frac{1}{10}$ Now, $P(X ≥ 6) =P(X= 6) + P(X = 7)$ $= 2k^2 + 7k^2 + k = 9k^2 + k =\frac{19}{100}$ $[∵k =\frac{1}{10}]$ |