Answer 1

Probability of any chosen month out of 12 months = \[\frac{1}{12}\]

There are seven possible ways in which a month can start and it will be a Friday on the 13^th day if the first day of the month is Sunday.
So, its probability = \[\frac{1}{7}\]

Thus, required probability = \[\frac{1}{12} \times \frac{1}{7} = \frac{1}{84}\]

Hence, the probability that the 13^th day of a randomly chosen month is Friday = \[\frac{1}{84}\]