Consider a probability distribution given by the density function \(𝑃(π‘₯)\).…

2025

Consider a probability distribution given by the density function \(𝑃(π‘₯)\).

\(P(x) = \begin{cases} Cx^2, & \text{for } 1 \leq x \leq 4 \\ 0, & \text{for } x < 1 \text{ or } x > 4 \end{cases} \)

The probability thatΒ \(x\) lies between 2 and 3, i.e.,Β \(𝑃(2 ≀ π‘₯ ≀ 3)\) is __________. (rounded off to three decimal places)

Attempted by 17 students.

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Correct answer: 0.302

Normalize the density to find the constant C:

Integrate the density over its support and set the total probability to 1:

  1. Compute ∫ from 1 to 4 of C xΒ² dx = 1. This gives C Β· [xΒ³/3]₁⁴ = 1.

  2. Evaluate the bracket: xΒ³/3 from 1 to 4 = (64/3) βˆ’ (1/3) = 63/3 = 21. So C Β· 21 = 1, hence C = 1/21.

Now compute the probability that x lies between 2 and 3:

  1. P(2 ≀ x ≀ 3) = βˆ«β‚‚Β³ (1/21) xΒ² dx = (1/21) Β· [xΒ³/3]β‚‚Β³.

  2. Evaluate: [xΒ³/3]β‚‚Β³ = (27/3) βˆ’ (8/3) = 19/3. So the probability is (1/21) Β· (19/3) = 19/63.

Numeric value rounded to three decimal places:

19/63 β‰ˆ 0.302

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