A, B, and C each drove 100-mile legs of a 300-mile course at speeds of 40, 50, and 60 miles per hour, respectively. What fraction of the total time did A drive ？（）

单项选择题A total of 40 brand X television sets and 80 brand Y television sets were purchased for a motel chain. If the price of each brand Y set was twice the price of each brand X set, what percent of the total bill was the price of a brand Y set ？（）

A．0.25%
B．0.5%
C．0.625%
D．0.833%
E．1.0%

单项选择题Of the science books in a certain supply room, 50 are on botany, 65 are on zoology, 90 are on physics, 50 are on geology, and 110 are on chemistry. If science books are removed randomly from the supply room, how many must be removed to ensure that 80 of the books removed are on the same science ？（）

A．81
B．159
C．166
D．285
E．324