A boat goes 100 km downstream in 10 hours, and 75 m upstream in 15 hours. The speed of the stream is? Choose the correct choice from the following answers.
A) 2 2 8/2
B) 2 2 1/9
C) 2 9 1/2
D) 2 2 1/2
E) 2 2 4/2
100 --- 10 2 2 1/2S = 10   ? ---- 1   75 ---- 15 US = 5   ? ----- 1 S = (10 - 5)/2   = 2 2 1/2kmph   Answer:2 2 1/2
<result>D</result>
A boat goes 100 km downstream in 10 hours, and 75 m upstream in 15 hours. The speed of the stream is?