Question

A probability experiment is conducted in which the sample space of the experiment is S={7,8,9,10,11,12,13,14,15,16,17,18}, event F={7,8,9,10,11,12}, and event G={11,12,13,14}. Assume that each outcome is equally likely. List the outcomes in F or G. Find P(F or G) by counting the number of outcomes in F or G. Determine P(F or G) using the general addition rule.

Answer 1

F or G = {7,8,9,10,11,12,13,14}

n(F or G) = 8

n(S) = 12

By counting the no. of outcome

P(F or G) = n(F or G) / n(S)

P(F or G) = 8 /12

P(F or G) = 2/3

By using the general addition rule

P(F or G) = P(F) + P(G) - P(F and G)

= 6/12 + 4/12 - 2/12

= 2/3