If a boat goes 7 km upstream in 42 minutes and the speed of the stream is 7 kmph, then the speed of the boat in still water is :
Choose one.
A) 2.5 km/hr
B) 4.5 km/hr
C) 5 km/hr
D) 10.5 km/hr
E) None of these
Solution   Speed of stream = 1/2 (17-8) km/hr= 4.5kmph . Answer 4.5 km/hr
<result>B</result>
If a boat goes 7 km upstream in 42 minutes and the speed of the stream is 7 kmph, then the speed of the boat in still water is :