Hello Davneet,
In this question,
Should we not consider the case that the man does not get a six at all in three throws of the die ?
That is I thought that the sample space of the experiment consists of {(6),(not 6,6),(not 6, not 6, 6), (not 6, not 6, not 6)} where 6 means he gets a six on a die and not 6 means he does not get a 6 ?
