If a boat goes 7 km upstream in 42 minutes and the speed of the stream is 4 kmph, then the speed of the boat in still water is :  Pick one:
A) 2.5 km/hr  B) 4.2 km/hr  C) 3 km/hr  D) 10.5 km/hr  E) None of these
Solution   Speed of stream = 1/2 (14-8) km/hr= 3kmph . Answer 3 km/hr
<result>C</result>
If a boat goes 7 km upstream in 42 minutes and the speed of the stream is 4 kmph, then the speed of the boat in still water is :