A man can row upstream at 7 km/h and downstream at 11 km/h. What is the man's rate in water?
Answer & explanation
Correct answer: option 1
Man's rate in water means speed of man. The speed will be same as that of speed of boat as he is sitting on the boat
Let,
Speed of boat in still water= x
Speed of stream/current = y
According to the question:
Upstream speed (Us) = 7 km/h i.e. x - y = 7 km/h -----1st equation
Downstream speed (Ds) = 11 km/h i.e. x + y = 11 km/h -----2nd equation
Adding both the equations:
x - y + x + y = 7 + 11
2x = 18
x = 9 km/h