what is the probability that the die lands on a 13 or a 1

Question

Suppose a special 14-sided die is rolled once where each face is marked with a number 1 through 14. What is the probability that the die lands on a 13 or a 1?

Answer 1

There is a total of 196 possibilities when rolling a 14-sided die.

P(1) = {(1, x) , (x, 1)} = 27/196

P(13) = {(13, x) , (x, 13)} = 27/196

P(1 and 13) = {(1, 13) , (13, 1)} = 2/196

x = number labeled from 1 through 14

Use the Addition Probability Rule.

P(1 or 13) = P(1) + P(13) - P(1 and 13) = 27/196 + 27/196 - 2/196 = 52/196 ≈ 0.2653

The probability that the die lands on a 13 or a 1 is 52/196 or 0.2653.