My Math Forum  

Go Back   My Math Forum > High School Math Forum > Probability and Statistics

Probability and Statistics Basic Probability and Statistics Math Forum


Thanks Tree1Thanks
  • 1 Post By Country Boy
Reply
 
LinkBack Thread Tools Display Modes
April 20th, 2018, 01:01 AM   #1
Member
 
Joined: Jan 2016
From: Blackpool

Posts: 97
Thanks: 2

Cumulative function question

A random variable has a cumulative distribution function

\[F_{X}(x)=c+de^{\frac{-x^2}{2}}\] if x>0 and 0 otherwise, what values must c and d have to make this a valid pdf?
Jaket1 is offline  
 
April 23rd, 2018, 07:08 AM   #2
Math Team
 
Joined: Jan 2015
From: Alabama

Posts: 3,261
Thanks: 894

The "cumulative probability function", $\displaystyle F_X(x)$, gives the probability that x< X. Now, you are told that the probability that x is negative is 0 so what is the probability that x< 0? What is $\displaystyle F_X(0)$ by this formula? Set those equal. Further, the total cumulative probability is 1. What is the limit of $\displaystyle F_X(x)$ as x goes to infinity? Set that equal to 1. Now you have two equations to solve for p and q.
Thanks from Jaket1
Country Boy is offline  
April 23rd, 2018, 12:20 PM   #3
Global Moderator
 
Joined: May 2007

Posts: 6,559
Thanks: 604

$F_X(\infty)=c=1,\ F_X(0)=c+d=0$
mathman is offline  
Reply

  My Math Forum > High School Math Forum > Probability and Statistics

Tags
cumulative, function, question



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
cumulative distribution function calypso Calculus 1 February 18th, 2017 12:06 AM
Cumulative distribution function yeaho26 Probability and Statistics 1 December 10th, 2016 01:12 PM
Cumulative distribution function help! (CDF) sharpknight Advanced Statistics 0 September 18th, 2014 11:18 PM
Cumulative dis function jsmith613 Algebra 2 February 16th, 2011 07:15 PM
cumulative distribution function question sneaky Algebra 1 October 8th, 2010 01:48 PM





Copyright © 2018 My Math Forum. All rights reserved.