Correct Answer - A
Let p be the probability of success in a trial. We have , `p=2(1-p)rArr =(2)/(3)`
Probability of r success in six trials is gven by
` P(X=r) =.^6C_r((2)/(3))^r((1)/(3))^(6-r)=.^6C_r2^r((1)/(3))^6`
`therefore` Required Probability `=P(Xge4)`
`P(X=4)+P(X=5)+P(X=6)`
`((1)/(3))^6(.^6C_4xx2^4+.^6C_5xx2^5+.^6C_5xx2^5+.^6C_5xx2^6)=(496)/(729)`