Eastern Airlines knows that 20% of its customers fly first class, 20% fly business class, and the rest fly coach. Of those customers who fly class, 70% are from the East Coast while 30% are from elsewhere. In addition, of those customers who fly business class, 50% are from the East Coast and 50% are from elsewhere.Finally, of those customers that fly coach class, 75% are from elsewhere and 25% are from the East Coast.

a. Construct a probabilit?y tree for this problem.