Suppose you ask a friend to randomly choose an integer between 1 and 10, inclusive. What is the probability that the number will be more than 5 or odd?

Answer 1

P(>5 or odd) = P(6,7, 8, 9, or 10 or 1, 3, or 5) = P( 1,3,5,6,7,8,9,10) = probability of 8 out of 10 possible numbers = 8/10 = .80 = 80%

= P(>5) + P(odd) - P(odd & >5)

= probability of each added together minus the probability of their overlap

= 1/2 + 1/2 - P(7 & 9)

= 1 - 2/10 = 8/10 = 80%