Answer
$\frac{1}{27}$
Work Step by Step
If A, B and C are independent events, then
P(E) = P(A)*P(B)*P(C)
E: green every time
A: green
B: green
C: green
P(A) = $\frac{2}{6}$
P(B) = $\frac{2}{6}$
P(C) = $\frac{2}{6}$
All of the events are independent of each other, so it follows that:
P(E) = $\frac{2}{6}$ .$\frac{2}{6}$ . $\frac{2}{6}$
= $\frac{1}{27}$