The value of k for which the function 

\(f\left( x \right) = \left\{ {\begin{array}{*{20}{c}} {k{e^{ - 3x}},}&{x > 0}\\ 0&{elsewhere} \end{array}} \right.\)

is probability density function, is

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Answer (Detailed Solution Below)

Option 3 : 3
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Detailed Solution

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Given

f(x) = { ke-3x, x > o

          { 0, elsewhere

Concept used

\(\smallint \limits_{ - \infty }^\infty f\left( x \right)dx \) = \( \smallint \limits_{ - \infty }^0 f\left( x \right)dx\) + \(\smallint \limits_0^\infty f\left( x \right)dx\) = 1

Calculation

According to given part

\(\smallint \limits_{ - \infty }^0 f\left( x \right)dx\) = 0

⇒ 0 + \( \smallint \limits_0^\infty f\left( x \right)dx\) = 0

∫ke-3xdx = 1

⇒ k[-e-3x/3]

⇒ -k/3[e-∞- e0] = 1

⇒ -k/3(0 – 1) = 1

⇒ k./3 = 1

The value of k = 3 for PDF

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