Math Main Page => Exercises - Math V-probability   Goal: to practise the probability of the events
Thursday September 02 2010 03:57:51 PM		Thursday September 02 2010 03:57:51 PM Flip Answers
[Assume one poll could poll out one and only one marble.]   If bagA contains marbles with three colors, 11 blue, 9 red and 3 green,     bagB contains marbles with three colors, 12 blue, 10 red and 5 brown,
1)	what's the probability of polling out one red marble in the first poll [From bagA]?		1) 11/23
2)	what's the probability of polling out one red marble first and then one blue marble in next poll [From bagA]?		2) (11*9)/(23*22)=9/46
3)	what's the probability of polling out three green marbles in the first three polls? [From bagA]		3) 3*2*1/(23*22*21)=1/1771
4)	what's the probability of polling out one red or blue marble in the first poll? [From bagA]		4) 20/23
5)	what's the probability of polling out three marbles one by one and they all are different colors? [From bagA]		5) 6*11*9*3/(23*22*21)=27/161
6)	what's the probability of polling out one marble each from two bags and both are red?		6) 11*12/(23*27)=44/207
7)	what's the probability of polling out one marble each from two bags and both are same color?		7) (11*12+9*10)/(23*27)=74/207
8)	what's the probability of polling out one marble each from two bags and they are different colors?		8) 1-(11*12+9*10)/(23*27)=133/207
Score: ______________

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