13i think u mean....
3/28x3/10+15/28x4/10+10/28x5/10
=17/40
An urn A contains 3 white and 5 red balls and another one B has 5 white and 3 red balls.2 balls are transferred from A to B and then 1 is drawn from B.What is the probability that it is red?
easy one but i 've a small doubt
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9 Answers
62prob of sending 2 whites
3/28x3/7+15/28x4/7+10/28x5/7
(9+60+50)/(28x7)
=17/28
1313but why 5C1*3C1/8C2=15/28
but not (5C1/8C1)*(3C1/8C1)=15/64
62because we are drawing 2 balls!
if you do that then there will be four cases
WR
RW
RR
WW
13but transferring two balls can mean just trasferring one ball and then another ball....so y not WR and RW
13but while we are picking them up...it must be one after another(without replacement)
13when we are picking it up...and selected one of the balls say with right hand then we can not choose that ball as the second one with left hand....no matter we r picking it up simultenously with left and right hand maybe