1.

Five marbles are drawn from a bag which contains 7 blue marbles and 4black marbles. What is the probability that: (i)all will be blue?(ii)3 will be blue and 2 black?

Answer» 1)Favorable cases=`.^7C_5`
Total=`.^11C_5`
`P=(.^7C_5)/(.^11C_5)`
2)7 blue balls=`.^7C_3`
4 black balls=`.^4C_2`
`P=(.^7C_3*.^4C_2)/(.^11C_5)`.


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