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a certain bag contains 6 marbles of which 4 are red and 2

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a certain bag contains 6 marbles of which 4 are red and 2  [#permalink]

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New post 23 Nov 2019, 12:13
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Question Stats:

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a certain bag contains 6 marbles of which 4 are red and 2 are white in color. if babu is to pick out two marbles from the bag simultaneously & at random, what is the probability that one is red & other one is white?
a. 1/5
b. 1/3
c. 1/15
d. 8/15
e. 4/9

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a certain bag contains 6 marbles of which 4 are red and 2  [#permalink]

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New post 24 Nov 2019, 04:08
jackfr2 wrote:
a certain bag contains 6 marbles of which 4 are red and 2 are white in color. if babu is to pick out two marbles from the bag simultaneously & at random, what is the probability that one is red & other one is white?
a. 1/5
b. 1/3
c. 1/15
d. 8/15
e. 4/9

Posted from my mobile device



Total ways to pick 2 marbles——-6C2=15
Ways to pick one of each ———-4C1*2C1=4*2=8

Probability =8/15

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Re: a certain bag contains 6 marbles of which 4 are red and 2  [#permalink]

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New post 24 Nov 2019, 04:11
1
jackfr2 wrote:
a certain bag contains 6 marbles of which 4 are red and 2 are white in color. if babu is to pick out two marbles from the bag simultaneously & at random, what is the probability that one is red & other one is white?
a. 1/5
b. 1/3
c. 1/15
d. 8/15
e. 4/9

Posted from my mobile device


Red & blue = 2c1 * 4/6 * 2/5 = 8/15
IMO D
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Re: a certain bag contains 6 marbles of which 4 are red and 2  [#permalink]

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New post 24 Nov 2019, 04:33
Probability of 1R and 1B = p(r)xP(b) +P(b)xP(r) as he can pick any ball first

case1 : red ball first and blue ball second = P(r)xP(b)=(2red/total 6) * 4 blue/5 total .....................1 ball has already been picked
case2 : blue ball first and red ball second =P(b)xP(r)= 4blue/total 6)* 2 red/5 total..........................1 ball has already been picked

required prob (case1 or case 2)= P(r)xP(b) +P(b)xP(r)= 4/15+ 4/15= 8/15.......(D)
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Re: a certain bag contains 6 marbles of which 4 are red and 2   [#permalink] 24 Nov 2019, 04:33
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a certain bag contains 6 marbles of which 4 are red and 2

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