Q. If $f(x) = \lambda e^{- ax}(a > 0)$ for $0 \leq x < \infty\$is a prabability density, then $\lambda$ is equal to

A) $a$
B) $a^{2}$
C) $\frac{1}{a}$
D) $a^{3}$
Explanation

(a)
Given, $f(x) = \lambda e^{- ax},for\ 0 \leq x < \infty\ and\ a > 0$
$\therefore\int_{0}^{\infty}{\lambda e^{- ax} = 1\ \ \lbrack\because}\ sum\ of\ total\ distribution\ is\ one\rbrack$
$\Rightarrow \ \lambda\left\lbrack \frac{e^{- ax}}{- a} \right\rbrack_{0}^{\infty} = 1$
$\Rightarrow \ \lambda\left\lbrack 0 + \frac{1}{a} \right\rbrack = 1 \Rightarrow \lambda = a$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.