My problem is in question X2.11's solution In (i) they have done it as Let X be the number of squares moved up the drain pipe each turn. Hence: X : -1 0 +1 +2 Probability : 1/6 5/12 1/3 1/12 My problem is how they got those probabilities. I have understood rest of the problem. Thanks in advance.
Just draw the sample space of the outcomes of roll of two dice (1,1),(1,2)........ (2,1),(2,2)....... . . . (6,1),(6,2)......(6,6) and then work out the probabilities. for example - 11 can come like this [ (5,6), (6,5) ] and 12 like this (6,6) So probability of (+2) movement = 3/36
I was calculating outcome of 11 and 12 as (5,6),(6,5) and (6,6),(6,6) respectively. And my probabilities were coming out as 4/36. My mistake. Thanks for the kind help.
