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Question

Let X denote the number of hours you play during a randomly selected day. The probability that X can take values x has the following form, where c is some constant:

\[ P(X = x) = \begin{cases} 0.1, & \text{if } x = 0 \\ cx, & \text{if } x = 1 \text{ or } x = 2 \\ c(5 - x), & \text{if } x = 3 \text{ or } x = 4 \\ 0, & \text{otherwise} \end{cases} \]

 

 

       

Match List-I with List-II:

List-IList-II
(A) c(I) 0.75
(B) P(X ≤ 2)(II) 0.3
(C) P(X = 2)(III) 0.55
(D) P(X ≥ 2)(IV) 0.15

Choose the correct answer from the options given below:

 

The correct answer is

(A) - (IV), (B) - (III), (C) - (II), (D) - (I)

To solve this problem, we will determine the constant \( c \) and calculate the probabilities as needed.

  1. The probability \( P(X = x) \) is given by:
    • \( P(X = 0) = 0.1 \)
    • \( P(X = 1) = c \times 1 = c \)
    • \( P(X = 2) = c \times 2 = 2c \)
    • \( P(X = 3) = c(5 - 3) = 2c \)
    • \( P(X = 4) = c(5 - 4) = c \)
  2. According to the properties of probability, \( \sum P(X = x) = 1 \). Therefore, we calculate:
\[0.1 + c + 2c + 2c + c = 1\]\[0.1 + 6c = 1\]
  1. Solving for \( c \):
\[6c = 0.9 \Rightarrow c = \frac{0.9}{6} = 0.15\]
  1. Next, calculate \( P(X \leq 2) \):
\[P(X = 0) + P(X = 1) + P(X = 2) = 0.1 + 0.15 + 0.3 = 0.55\]
  1. Calculate \( P(X = 2) \):
\[P(X = 2) = 2c = 2 \times 0.15 = 0.3\]
  1. Calculate \( P(X \geq 2) \):
\[P(X = 2) + P(X = 3) + P(X = 4) = 0.3 + 0.3 + 0.15 = 0.75\]

\((A) - (IV), (B) - (III), (C) - (II), (D) - (I)\) is correct .

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Important Questions from Probability

  1. A die is rolled thrice. What is the probability of getting a number greater than 4 in the first and the second throws, and a number less than 4 in the third throw?

  2. Two dice are thrown simultaneously. If \( X \) denotes the number of fours, then the expectation of \( X \) will be:

  3. If the random variable \( X \) has the following distribution:

    X012otherwise
    P(X)k2k3k0

     

     

    Match List-I with List-II:

    List-IList-II
    (A) k(I) \(\frac{5}{6}\)
    (B) P(X < 2)(II) \(\frac{4}{3}\)
    (C) E(X)(III) \(\frac{1}{2}\)
    (D) P(1 ≤ X ≤ 2)(IV) \(\frac{1}{6}\)

    Choose the correct answer from the options given below:

     

  4. For the differential equation \( (x \log_e x) dy = (\log_e x - y) dx \):

    (A) Degree of the given differential equation is 1.

    (B) It is a homogeneous differential equation.

    (C) Solution is \( 2y \log_e x + A = (\log_e x)^2 \), where A is an arbitrary constant.

    (D) Solution is \( 2y \log_e x + A = \log_e (\log_e x) \), where A is an arbitrary constant.

    Choose the correct answer from the options given below:

  5. Which of the following is the probability of \( x \) successes in a binomial distribution with number of trials \( n \) and probability of success as \( \theta \) ( \( 0 < \theta < 1 \) ) in each trial?

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