Question

The table gives a set of outcomes and their probabilities. Let A be the event "the outcome is greater than or equal to 4". Let B be the event "the outcome is less than or equal to 4". Find P(A or B).
Outcome Probability
1 0.33
2 0.44
3 0.08
4 0.02
5 0.04
6 0.09

Answer 1

A = {4,5,6}, B = {1,2,3,4}. A ∪ B = {1,2,3,4,5,6} is the whole sample space, so P(A or B) = 1.

(Or compute: P(A)=0.02+0.04+0.09=0.15, P(B)=0.33+0.44+0.08+0.02=0.87, P(A∩B)=P(4)=0.02, so P(A∪B)=0.15+0.87−0.02=1.0.)