For the second part you pick a car after your friend picks a goat.

              FRIEND
 P[Car] = 1/3        P[Goat]=2/3
                        YOU
             P[Car]=1/2     P[Goat]=1/2

Use this as a binary transmission system, so P[Car|Friend chooses Goat] = (2/3)(1/2) = 1/3

Alumni Liaison

Ph.D. 2007, working on developing cool imaging technologies for digital cameras, camera phones, and video surveillance cameras.

Buyue Zhang