A bag contains 5 white and 3 black balls. Four balls are successively
drawn out without replacement. What is the probability that they are
alternately of different colours?
Here, `W_(1)` = {4 white balls} and `B_(1)`={5 black balls}
and `W_(2)` = {9white balls} and `B_(2)` = {7 black balls}
Let E, is the event that ball transferred fram...
Bag I ={3B,2W],Bag II={2B,4W}
Let `E_(1)`=Event that bag I is selected
`E_(2)`=Event that bag II is selected
and E=Event that a black ball is selected
`rArrP(E_(1))=1//2,P(E_(2))=1/2,P(E//E_(1))=3/5,P(E//E_(2))=2/6=1/3`
`thereforeP(E)=P(E_(1))cdotP(E//E_(1))+P(E_(2))cdotP(E//E_(2))`
`1/2cdot3/5+1/2cdot2/6=3/10+2/12`
`=(18+10)/60=28/60=7/15`
Let `U_(1)`={2 white, 3 black balls}
`U_(2)`={3 white , 2 black balls}
and `U_(3)`={4 white ,1 black balls}
`thereforeP(U_(1))=P(U_(2))=P(U_(3))=1/3`
Let `E_(1)` be the event that a ball is chosen from...
Probability of drawing 2 green balls and one blue ball
`=P_(G)cdotP_(G)cdotP_(B)+P_(B)cdotP_(G)cdotP_(G)+P_(G)cdotP_(B)cdotP_(G)`
`=3/8cdot2/7cdot2/6+2/8cdot3/7cdot2/6+3/8cdot2/7cdot2/6`
`=1/28+1/28+1/28=3/28`
Correct Answer - `(10)/(91)`
The required probability is
`(.^(3)C_(3) + .^(7)C_(3) + .^(4)C_(3))/(.^(14)C_(3)) = (1 + 35 + 4)/(14 xx 13 xx 2) = (40)/(14 xx 26) = (10)/(91)`
Let A nad B denote, respectively, the events that first ball drawn is black and second ball drawn in white.
We have to find `P(AnnB) or P(AB).`
` P(AnnB)P(A)P(B//A)`
Now,...
Procedure of drawing th balls has to end at the rth draw. So, exactly two black balls are drawn in first (r-1) draws and third black ball is drawn in...
Correct Answer - B
The required probability is
`(n^(2))/(""^(2n)C_(2))((n-1)^(2))/(""^(2n-2)C_(2))((n-2)^(2))/(""^(2n-4)C_(2))...(2^(2))/(""^(4)C_(2))(1^(2))/(""^(2)C_(2))`
`=((1xx2xx3xx4xx...xx(n-1)n)^(2))/(((2n)!)/2^(n))=(2^(n)(n!)^(2))/((2n)!)=(2^(n))/(""^(2n)C_(n))`