11. Ted's grandfather exercised on a treadmill for three days, running 2 miles each day. It is known that the speeds on the first, second, and third days were 5 miles/hour, 3 miles/hour, and 4 miles/hour, respectively. If his grandfather maintained a speed of 4 miles/hour throughout, he would have spent ( ) minutes less on the treadmill.
(A) 1
(B) 2
(C) 3
(D) 4
(E) 5
11. D.

According to the problem, the required calculation is $\frac{2}{5}+\frac{2}{3}+\frac{2}{4}-\frac{6}{4}=\frac{1}{15}$ (hour) $=4$ (minutes).