33.
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 : . [C.B.I. 1993]
4.2
km/hr 13 km/hr
9
km/hr 21 km/hr
Answer: 13 km/hr
Explanation: Rate upstream = (7/42)*60 kmh = 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.
