The probability density function of a random variable X is f(x) = \(\frac{\pi}{10} sin \frac{\pi x}{5}\); 0 ≤ x ≤ 5. The first quartile of X is:

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SSC CGL JSO Tier-II, 2018 (Statistics) Official Paper-III (Held On: 14 Sept, 2019)
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  1. \(\frac{10}{3}\)
  2. 1.25
  3. \(\frac{1}{5}\)
  4. \(\frac{5}{2}\)

Answer (Detailed Solution Below)

Option 2 : 1.25
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Detailed Solution

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Calculation:

To find the first quartile of X, we need to find the value x such that the area under the probability density function f(x) to the left of x is 0.25.

We can begin by finding the cumulative distribution function (CDF) of X:

F(x) = ∫[0, x] f(t) dt

Since f(x) is a uniform distribution between 0 and 5, we have:

f(x) = 1/5 for 0 ≤ x ≤ 5

Therefore, the CDF of X is:

F(x) = ∫[0, x] (1/5) dt = x/5

To find the first quartile of X, we need to find the value x such that:

F(x) = x/5 = 0.25

Solving for x, we get:

x = 0.25 × 5 = 1.25

Therefore, the first quartile of X is 1.25.

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