
Probability and Statistics Basic Probability and Statistics Math Forum 
 LinkBack  Thread Tools  Display Modes 
April 30th, 2017, 06:23 AM  #1 
Newbie Joined: Apr 2017 From: Britain Posts: 1 Thanks: 0  A simple problem?
Hello everyone, I'd like to know how to calculate an expected value for the number of a population with a particular property. Let's suppose that for the whole population of a country 20% of those who choose to study a subject, let's say mathematics at A level, are female. (Let's say the population has a 1:1 ratio of male:female as a whole, though I'd also like to account for there being a 51:49 ratio or such nationally). If I take a year group that has 50 males and 50 females, I'd expect the 4:1 ratio of male:female choosing to study maths, regardless of the total number that choose it. What if my group doesn't have a 1:1 ratio, but instead has say 40% males and 60% females. What proportion of males and females would I expect to choose maths? Would it be 24%, as an additional fifth of female population are there with the same expected chance of choosing maths? What would be the general formula for working out the expected proportion of m:f in a subject, given an initial proportion of m:f in the yearvgroup? Thanks for any help everyone. EP 

Tags 
problem, simple 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Please help with simple problem.  ashantt  Algebra  1  May 15th, 2013 07:18 AM 
Simple Problem!  ZardoZ  Algebra  7  September 12th, 2012 07:18 AM 
Help with a simple problem  ca777  Algebra  5  November 2nd, 2010 09:36 PM 
Simple help problem.  David_Lete  Algebra  5  December 1st, 2009 01:08 AM 
Looks like a simple problem, but...  The HitchHiker  Algebra  6  August 18th, 2008 01:55 AM 