Statistics - Probability

Question

Sam and Tina both have intentions to a Christmas party. The probability that Sam will go is 0.2. The probability that Tina will go is 0.9 if Sam goes, and 0.3 is Sam does not go.

a) What is the probability that both Sam and Tina are at the party?
b) What is the probability that only one of them goes to the party?
c) What is the probability that Sam went to the party given that Tina did?

Answer 1

A) 0.2 * 0.9 = 0.18

B) ( 0.2 * 0.1 ) + ( 0.8 * 0.3 ) = ( 0.02 + 0.24 ) = 0.26