Marble Probability Queston

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Mitsukuni

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Jun 25, 2015
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Question: A box contains 8 marbles and 4 white marbles. If 2 marbles are selected at random, find the probability that
A) all are blue
B) they are different colours
C) at least 1 is blue


I'm not sure if there's a typo and its actually 8 blue marbles but I'm assuming there's no typo.
 
Mitsukuni said:
Question: A box contains 8 marbles and 4 white marbles. If 2 marbles are selected at random, find the probability that
A) all are blue
B) they are different colours
C) at least 1 is blue


I'm not sure if there's a typo and its actually 8 blue marbles but I'm assuming there's no typo.
Click to expand...
I think you're right that it's a typo. But, to be sure, contact your instructor about the issue. "Are there eight marbles, four of which are white, and I'm supposed to assume that the other four are blue? Or are there eight blue marbles and four white marbles?"

Your instructor may not be aware of the issue, and you're likely not the only student in class who's confused! ;)
 
Mitsukuni said:
Question: A box contains 8 marbles and 4 white marbles. If 2 marbles are selected at random, find the probability that
A) all are blue
B) they are different colours
C) at least 1 is blue
I'm not sure if there's a typo and its actually 8 blue marbles but I'm assuming there's no typo.
Click to expand...
There is NO TYPO. Two marbles are selected. the "all" refers to those two.
It would have been better to write "both".
 
Mitsukuni said:
Question: A box contains 8 marbles and 4 white marbles. If 2 marbles are selected at random, find the probability that
A) all are blue
B) they are different colours
C) at least 1 is blue


I'm not sure if there's a typo and its actually 8 blue marbles but I'm assuming there's no typo.
Click to expand...

Just to add to the confusion - if its actually a total of 8 marbles and there are 4 white marbles are there exactly 4 white marbles? After all if there were 8 marbles and all were white there would be 1 white marble but there would also be 8 white marbles:confused:
 
Denis said:
Pka...to the corner !
Click to expand...
That is just dumb of you and others here.
Clearly it was not a typo, it was a word drop: 8 blue marbles and 4 white marbles.
After all 4+8=12.
 
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