1.

A box contains 5 green ,4 yellow and 3 whitemarbles ,Three marblesaredrawn at random, whatis theprobability thatthey are notof thesamecolour ?

Answer»

`40//44`
`44//41`
`41//44`
`40//39`

Solution :`n(E) =""^(5)C_(3)+""^(4)C_(3) +""^(3)C_(3)=10+4+1=15`
`n(S) =""^(12)C_(3)=220`
`P=(n(E))/(n(S))=(15)/(220)=(3)/(44)`
(it is probability whenall 3 areof same COLOUR )
`therefore ` Requiredprobability`=1-(3)/(44)=(41)/(44)`


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