My Math Forum  

Go Back   My Math Forum > High School Math Forum > Pre-Calculus

Pre-Calculus Pre-Calculus Math Forum


Thanks Tree1Thanks
  • 1 Post By romsek
Reply
 
LinkBack Thread Tools Display Modes
November 6th, 2016, 02:32 PM   #1
Senior Member
 
Joined: Feb 2014

Posts: 112
Thanks: 1

Problem with expected value in Geometric distribution

Hello,
Could you explain red line in the below image?
What we used derivative?
Thanks
Attached Images
File Type: jpg redddd.JPG (32.2 KB, 5 views)
life24 is offline  
 
November 6th, 2016, 04:12 PM   #2
Senior Member
 
romsek's Avatar
 
Joined: Sep 2015
From: USA

Posts: 1,649
Thanks: 837

what exactly don't you understand?

can you recognize that

$-\dfrac{d}{dp}(1-p)^n = n(1-p)^{n-1}$ ?
Thanks from life24
romsek is offline  
November 6th, 2016, 10:32 PM   #3
Senior Member
 
Joined: Feb 2014

Posts: 112
Thanks: 1

Quote:
Originally Posted by romsek View Post
what exactly don't you understand?

can you recognize that

$-\dfrac{d}{dp}(1-p)^n = n(1-p)^{n-1}$ ?
Thank you,
Negative come from?
And why in first summation start from 1 then became 0 ?
life24 is offline  
November 6th, 2016, 10:34 PM   #4
Senior Member
 
romsek's Avatar
 
Joined: Sep 2015
From: USA

Posts: 1,649
Thanks: 837

Quote:
Originally Posted by life24 View Post
Thank you,
Negative come from?
the $-p$ in $(1-p)$

It really should have been 0 all along but since there was a factor of $n$ in the earlier expressions the 0th term was 0 and was left out.

Last edited by romsek; November 6th, 2016 at 10:36 PM.
romsek is offline  
Reply

  My Math Forum > High School Math Forum > Pre-Calculus

Tags
distribution, expected, geometric, problem



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Expected value - above a certain amount - Normal Distribution Peno77 Probability and Statistics 4 February 19th, 2015 05:45 AM
Geometric distribution fatalaccidents Algebra 4 January 30th, 2013 02:37 PM
i.i.d. distribution and its expected value cloudtifa Advanced Statistics 2 October 14th, 2010 07:52 AM
CDF of geometric distribution chanys Algebra 2 November 28th, 2009 08:51 PM
The expected gain, given a Binomial Distribution? Zephyr Advanced Statistics 1 October 2nd, 2007 06:44 PM





Copyright © 2017 My Math Forum. All rights reserved.