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November 27th, 2007, 11:29 PM   #1
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help pls !!! asap

prove that

one over square root of two pi times the integral of e raise to negative one half x squared, dx from positive infinity to negative infinity is equal to one.
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November 28th, 2007, 07:00 AM   #2
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The integrand is the normal distribution's pdf. The fact that the integral is 1 means that there's a 100% chance of a normally distributed value falling from -infty to +infty.

you can probably Google for a proof.
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November 28th, 2007, 02:54 PM   #3
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Re: help pls !!! asap

Quote:
Originally Posted by haruka-san
prove that

one over square root of two pi times the integral of e raise to negative one half x squared, dx from positive infinity to negative infinity is equal to one.
The simplest proof involves squaring the integral, so that it is a double integral in x and y, then convert to polar coordinates. This integral can be evaluated anaytically.
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