A garage sells tires of types A. B, and C, and the owner surmises that a customer

Question:

A garage sells tires of types A. B, and C, and the owner surmises that a customer is twice as likely to choose type A as type B, and twice as likely to choose type B as type C.
(a) Is this supposition plausible based upon the data set in DS 10.3.3 of this year's sales?
(b) Calculate a 99% two-sided confidence interval for the probability that a customer chooses type A tires.