Question

An urn contains 78 slips of paper. Each slip bears a number from 1 to 26. Each number appears on 3 different slips. A child selects two slips of paper at random and without replacement. Find the probability that the drawn slips have the same number. Write your answer as a reduced fraction.

Answer 1

2 / 77

Explanation:

Each number appears 3 times in the urn.

After picking any number, the number picked will appear only two more times in the urn, and the total slips of paper will be 77.

So for any first number we pick, the probability of the second number picked being the same number as the first pick is the number of times the same number appears in the urn (2) over the total number of slips in the urn (77):

Probability = 2 / 77