Question

tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random what is the probability that the ticket drawn has a number which is multiple of 3 and 5?​

Answer 1

Total number of outcome = 20

Probability of picking multiple of 3 out of 1 - 20 = (6 items of 20) = 6/20

Probability of picking multiple of 5 out of 1 - 20 = (4 items of 20) = 4/20

Therefore p(multiples of 3 or 5) = 6/20 + 4/20 = 10/20 = 1/2.