P(red) = 1/6
P(green) = 1/3
P(blue) = 1/6
P(yellow) = 1/3
Thrown 11 times but only 6 times will you get yellow. This means that 5 other times you have to get any colour but yellow and the probability of landing any colour other than yellow is 2/3. Have to consider the combinations too.
Pr (yellow only 6 times) = 1/3 x 1/3 x 1/3 x 1/3 x 1/3 x 1/3 x 2/3 x 2/3 x 2/3 x 2/3 x 2/3 x 11C6 = 0.083456
I hope this is right! >.