A bag contains six marbles: two red, two blue, and two green. If two marbles are drawn at random, what is the probability that they are the same color?
oa: [spoiler]1/5[/spoiler]
i keep on getting 1/15???
how should i tackle these pair problems.
probability 2
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- nithi_mystics
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Prob. of getting two red balls = 2C2/6C2 = 1/15
p(2 blue balls) = p(2 green balls) = 1/15
Prob of getting 2 balls of the same color = 1/15 + 1/15 + 1/15 = 1/5
p(2 blue balls) = p(2 green balls) = 1/15
Prob of getting 2 balls of the same color = 1/15 + 1/15 + 1/15 = 1/5
Thanks
Nithi
Nithi
Total way to select 2 marbles 6!/4!2!=15Gurpinder wrote:A bag contains six marbles: two red, two blue, and two green. If two marbles are drawn at random, what is the probability that they are the same color?
oa: [spoiler]1/5[/spoiler]
i keep on getting 1/15???
how should i tackle these pair problems.
Fav way to select 2 marble 3 only 3 set of same color marble.
Prob = 3/15 = 1/5
- Gurpinder
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but doesent the problem say that you pick 2 balls at random. so doesent that mean that your choice on the first ball will effect the options for the next selection. thats what i was doing.nithi_mystics wrote:Prob. of getting two red balls = 2C2/6C2 = 1/15
p(2 blue balls) = p(2 green balls) = 1/15
Prob of getting 2 balls of the same color = 1/15 + 1/15 + 1/15 = 1/5
1/3 for 1st selection.
1/5 for 2nd selection
= 1/15
- jeffedwards
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Just think of it this way, it doesn't matter what color you chose first, so ignore that.
No suppose you chose any color, what is the probability of choosing a match....1/5
Because you have one marble that will match that selection out of a total of 5 marbles left.
No suppose you chose any color, what is the probability of choosing a match....1/5
Because you have one marble that will match that selection out of a total of 5 marbles left.
- Gurpinder
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what if the ratio of color of balls was different?jeffedwards wrote:Just think of it this way, it doesn't matter what color you chose first, so ignore that.
No suppose you chose any color, what is the probability of choosing a match....1/5
Because you have one marble that will match that selection out of a total of 5 marbles left.
- jeffedwards
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Gurpinder wrote:what if the ratio of color of balls was different?jeffedwards wrote:Just think of it this way, it doesn't matter what color you chose first, so ignore that.
No suppose you chose any color, what is the probability of choosing a match....1/5
Because you have one marble that will match that selection out of a total of 5 marbles left.
Good question
Then you would have to do the probability separate. So in this case you would solve the problem just as nithi_mystics.
Probability of red 2/6 or 1/3
Probability of red again 1/5
Times it (1/3)*(1/5) = 1/15 (That's the probability of drawing red and red again)
Repeat the process for all three colors and add the results
(1/15)+ (1/15)+ (1/15) = 3/15 = 1/5
1/5 is your answer