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June 7th, 2019, 07:21 AM  #1 
Member Joined: Apr 2017 From: India Posts: 67 Thanks: 0  Probability
This question is from my examination paper: One bag contains 4 white and 3 black balls and a second bag contains 3 white and 5 black balls. One ball is drawn from the first bag and placed unseen in the second bag. What is the probability that a ball now drawn from the second bag is black ? My final answer was 38/63. Can someone please check that for me whether I answered it correctly or not? 
June 7th, 2019, 09:47 AM  #2 
Senior Member Joined: Sep 2015 From: USA Posts: 2,452 Thanks: 1337 
$\dfrac 4 7\dfrac 5 9 + \dfrac 3 7 \dfrac 6 9 = \\ \dfrac{20}{63}+\dfrac{18}{63} = \dfrac{38}{63}$ well done 
June 7th, 2019, 10:29 AM  #3 
Senior Member Joined: Dec 2015 From: somewhere Posts: 534 Thanks: 81 
I worship cats too . 

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