Target Exam

CUET

Subject

-- Applied Mathematics - Section B2

Chapter

Probability Distributions

Question:

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 atmost two hours of television on a selected day?

Options:

$\frac{8}{25}$

$\frac{17}{25}$

$\frac{3}{25}$

$\frac{7}{25}$

Correct Answer:

$\frac{17}{25}$

Explanation:

The correct answer is Option (2) → $\frac{17}{25}$

From the given information, we find that the probability distribution of X is

X

0

1

2

3

P(X)

0.2

k

2k

2k

We know that $Σp_i = 1$

$⇒ 0.2+k+2k + 2k = 1$

$⇒ 5k=0.8⇒k=\frac{4}{25}$

P(the person watches atmost two hours of television)

$= P(X ≤ 2) = P(X = 0) + P(X = 1) + P(X = 2)$

$= 0.2 + k + 2k$

$= 0.2 + 3k =\frac{1}{5}+\frac{12}{25}=\frac{17}{25}$