Question

You are rolling one die. Let event A = rolling a six and let event B = rolling a number less than

four. What is the probability of A or B?

Answer 1

2/3

Explanation:

A = rolling a six

B = rolling a number less than 4

Probability of A or B

P(A) or P(B) = P(A) + P(B) - P(AnB)

Probability = (number of required outcome / Total possible outcomes)

P(A) = 1 / 6

P(B) :

Required outcomes = (3, 2, 1) = 3

P(B) = 3/6 = 1/2

P(AnB) = A={6} ; B = {1,2,3} ; AnB = {}

P(AnB) = 0

Hence,

P(A) or P(B) = 1/6 + 1/2 - 0

= (1 + 3) / 6

= 4/ 6

= 2/3