Math, asked by sandhya16, 1 year ago

verify that the following are probability density function.
F(x)=1/π 1/π(1+x^2),-∞‹x‹∞


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Answers

Answered by kvnmurty
2
Probability density function has a value between 0 and 1. The (sum of) total value of probability for all values in the domain of x, is always 1.  So we need to check that.

f(x) =  1/π * 1/(1+x²)     ,   -∞ < x < ∞
        1+x² > 1.  Hence f(x) < 1 for  x
         f(x) is defined for each value of x in the domain.

Cumulative probability function:

F(x)= \int \limits_{-\infty}^{x} {f(x)} \, dx\\\\=\frac{1}{\pi}\int \limits_{-\infty}^{x} {\frac{1}{1+x^2}} \, dx\\\\=\frac{1}{\pi} [ tan^{-1} x]_{-\infty}^{x}\\\\=\frac{1}{\pi} [ Tan^{-1} x+\frac{\pi}{2}]\\\\So \ F(-\infty)=0, \ F(0)=\frac{1}{2}, \ F(\infty)=1\\

Hence,  f(x) is a probability density function.

The mean μ of the distribution is  x=0, as cumulative probability is 1/2 for x=0.

kvnmurty: click on red heart thanks above pls
sandhya16: done
kvnmurty: is this ans helpful ? is that clear and comprehensible?
kvnmurty: sorry i did not see this qn before..i saw it late
sandhya16: kk
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