This is the solution to the problem posted at https://learn1.open.ac.uk/mod/oublog/viewpost.php?post=279732
When two dice are rolled there are 6 x 6 = 36 possible outcomes, all equally likely. However the information that at least one has come up six narrows down the number of possibilities to the 11 shown as crosses below.
1 | 2 | 3 | 4 | 5 | 6 | |
---|---|---|---|---|---|---|
1 | x | |||||
2 | x | |||||
3 | x | |||||
4 | x | |||||
5 | x | |||||
6 | x | x | x | x | x | x |
Of these both dice show 6 in only one case, so the required probability is 1/11 ~ 9%.