
PreCalculus PreCalculus Math Forum 
 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 
November 6th, 2016, 04:12 PM  #2 
Senior Member Joined: Sep 2015 From: USA Posts: 1,649 Thanks: 837 
what exactly don't you understand? can you recognize that $\dfrac{d}{dp}(1p)^n = n(1p)^{n1}$ ? 
November 6th, 2016, 10:32 PM  #3 
Senior Member Joined: Feb 2014 Posts: 112 Thanks: 1  
November 6th, 2016, 10:34 PM  #4 
Senior Member Joined: Sep 2015 From: USA Posts: 1,649 Thanks: 837  the $p$ in $(1p)$ 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. 

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 