Let X denote the number of hours a person watches television during a randomly selected day. The probability that X can take the values $x_i$ has the following form, where k is some unknown constant. $P(X = x;) =\left\{\begin{matrix}0.2,&if\,x_i=0\\Kx_i,& if\, x_i = 1\, or\, 2\\k (5-x_i),&if\, x_i = 3\\0,&otherwise\end{matrix}\right.$ What is the probability that the person watches two hours of television on a selected day? |
$\frac{1}{25}$ $\frac{8}{25}$ $\frac{6}{25}$ $\frac{3}{25}$ |
$\frac{8}{25}$ |
The correct answer is Option (2) → $\frac{8}{25}$ From the given information, we find that the probability distribution of X is
We know that $Σp_i = 1$ $⇒ 0.2+k+2k + 2k = 1$ $⇒ 5k=0.8⇒k=\frac{4}{25}$ Probability that the person watches two hours of television $= P(X = 2)=2k = 2 ×\frac{4}{25}=\frac{8}{25}$ |