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Let X denote the number of hours a person watches television during a randomly selected day. The probability that X can take the value xix_i, has the following form, where kk is some unknown constant.

P(X=xi)={0.5if xi=0kxiif xi=1k(4−xi)if xi=2 or 30otherwiseP(X=x_i) = \begin{cases} 0.5 & \text{if } x_i=0 \\ kx_i & \text{if } x_i=1 \\ k(4-x_i) & \text{if } x_i=2 \text{ or } 3 \\ 0 & \text{otherwise} \end{cases}

The probability that the person watches at most 2 hours of television on a selected day is :

Solution

✅ Correct Option: 2

The probabilities are 0.50.5, kk, 2k2k and kk, summing to 11, so 4k=0.54k = 0.5 and k=18k = \frac{1}{8}. Then P(X≤2)=0.5+18+28=78P(X\le2) = 0.5 + \frac{1}{8} + \frac{2}{8} = \frac{7}{8}.

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