My Math Forum  

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

Probability and Statistics Basic Probability and Statistics Math Forum


Reply
 
LinkBack Thread Tools Display Modes
May 14th, 2014, 11:43 AM   #1
Newbie
 
Joined: May 2014
From: england

Posts: 11
Thanks: 0

Exclamation independent events rule question - please please help as exam tomorrow!

For 2 independent events, A and B, p(AuB')=0.7 and P(A)=0.5. A and B are independent. Find the probability of event B happening.?

I do not understand this question, sorry.

The markscheme working is (0.3+x)0.5=x
0.15 = 0.5x
x=0.3
p(B)=0.6

if this is the independent events rule, where does b being 0.3+x come from please?

id really appreciate a step-by-step response

thanks!
rhubarb123 is offline  
 
May 14th, 2014, 12:52 PM   #2
Global Moderator
 
Joined: May 2007

Posts: 6,807
Thanks: 717

I don't where the formula came from.

My approach:
P(A∪B') = P(A) + P(B') - P(A∩B')
P(A∩B') = P(A)P(B') (independence)
Let x = P(B')
.7 = .5 + x - .5x
x = .4
P(B) = 1-x = .6
mathman is offline  
May 15th, 2014, 01:25 AM   #3
Newbie
 
Joined: May 2014
From: england

Posts: 11
Thanks: 0

thanks

thanks a lot! understood
rhubarb123 is offline  
Reply

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

Tags
events, exam, independent, question, rule, tomorrow



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Exam Tomorrow! Need Help :( Chriiisss Applied Math 0 April 21st, 2013 04:36 PM
Independent events Keroro Algebra 1 June 6th, 2012 08:17 AM
Question before math exam tomorrow csoles Elementary Math 1 March 20th, 2012 08:03 PM
Pls help! tomorrow i have EXAM! help in homework! :( kabal Calculus 2 May 22nd, 2010 05:37 PM
Independent events Siria Advanced Statistics 4 July 5th, 2009 09:21 AM





Copyright © 2019 My Math Forum. All rights reserved.