If a boat goes 7 km upstream in 42 minutes and the speed of the stream is 3 kmph, then the speed of the boat in still water is
Choose the correct choice from the following choices.
A) 12 kmph  B) 13 kmph  C) 14 kmph  D) 15 kmph  E) None of these
Explanation:   Rate upstream = (7/42)*60= 
<gadget id="calculator">(7/42)*60</gadget>
<output>10</output>
10 kmph.   Speed of stream= 3 kmph.   Let speed in sttil water is x km/hr   Then, speed upstream = (x —3) km/hr.   x-3 = 10 or x = 13 kmph   Option 13 kmph
<result>B</result>
If a boat goes 7 km upstream in 42 minutes and the speed of the stream is 3 kmph, then the speed of the boat in still water is