The easiest way to calculate this is to find the probability that <em>none</em> of the cubes show a 2. The probability that a cube doesn't show a 2 is 11/12.
0.7703. Now we have to subtract this value from one which gives us 0.2297. Hope this helps
You have to divide 5 hours by 1/3 hours because you are finding out how many 1/3's you need to get 5. 5 / 1/3 You then have to do copy, dot, flop 5 x 3/1 and multiply to get 15 nights
