My Math Forum Affine transformation

 January 27th, 2017, 11:58 PM #1 Member   Joined: Jan 2017 From: California Posts: 31 Thanks: 2 Affine transformation Hi guys am stuck on this one If $E(X)=3$ and $Var(X)=2$ what is $E((2+5X)^2)$
 January 28th, 2017, 12:05 AM #2 Senior Member     Joined: Sep 2015 From: CA Posts: 1,109 Thanks: 580 $E[(2+5X)^2] = E[4+10X + 25X^2] = 4 + 10E[X] + 25 E[X^2]$ $E[X^2] = Var[X] + (E[X])^2 = 2 + 3^2 = 11$ $4 + 10E[X] + 25 E[X^2] = 4 + 10(3) + 25(11) = 309$ Thanks from dthiaw
January 28th, 2017, 12:23 AM   #3
Member

Joined: Jan 2017
From: California

Posts: 31
Thanks: 2

Quote:
 Originally Posted by romsek $E[(2+5X)^2] = E[4+10X + 25X^2] = 4 + 10E[X] + 25 E[X^2]$ $E[X^2] = Var[X] + (E[X])^2 = 2 + 3^2 = 11$ $4 + 10E[X] + 25 E[X^2] = 4 + 10(3) + 25(11) = 309$
I ll replace the 10 with 20 on the distribution. You are a superstar man. Thanks a bunch

 Tags affine, transformation

 Thread Tools Display Modes Linear Mode

 Similar Threads Thread Thread Starter Forum Replies Last Post ggyyree Calculus 0 July 27th, 2010 04:59 AM maximilian Algebra 0 June 18th, 2010 11:50 AM arnav.akash9 Linear Algebra 0 November 17th, 2009 04:41 PM nooblet Number Theory 3 March 12th, 2009 03:46 AM dervish Algebra 0 May 23rd, 2008 07:23 AM

 Contact - Home - Forums - Top