Question

A box contains 5 green ,4 yellow and 3 white marbles ,Three marbles are drawn at random , what is the probability that they are not of the same colour ?
A. `40//44`
B. `44//41`
C. `41//44`
D. `40//39`

Answer 1

Correct Answer - C
`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 when all 3 are of same colour )
`therefore ` Required probability `=1-(3)/(44)=(41)/(44)`