Of two dominoes taken at random, one is turned over. Determine the probability that the second

Of two dominoes taken at random, one is turned over. Determine the probability that the second die is a double if the first is not a double.

1. Out of 28 dominoes in a standard set, 7 are doubles. If it is known that one of the two dice taken at random is not a double, then we can assume that the second dice is chosen from the remaining 27 dice, among which there are still 7 duplicates.

2. Consequently, the probability of event A, that the second dice is a double, is equal to the ratio of the number of duplicates to the total number of remaining dice:

P (A) = 7/27.

Answer: 7/27.