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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. Rakesh is 17th from the right and Ankit is 15th from the left in a line of students. If they interchange their places, the position of Ankit becomes 19th from the left. How many students are there in the line?

  2. What comes in place of the question mark (?) in the series given below?

    B2D, C3F, E5J, G7N, ?, M13Z

  3. If 1st January, 2001 was a Monday, what was the day on 26th January, 2003?

  4. From the given options, at what angle are the hands of a clock inclined at 10 minutes to 2 (Smaller angle)?

  5. In the given analogy, choose the number which will replace the question mark (?).

    WSH : 5 : : KMJ : ?

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