A boat runs at 22 km per hour along the stream and 10 km per hour against the stream. Find the ratio of speed of the boat in still water to that of the speed of the stream.

Speed along the stream = speed downstream = a
= 22 km/hr
And speed against the stream = speed upstream = b
= 10 km/hr.
Now, the speed in still water = (a + b)/2 km/hr
= (22 + 10)/2
= 16 km/hr.
And the speed of stream = (a - b)/2 km/hr
= (22 - 10)/2
= 6 km/hr.
Required ratio = speed in still water : speed of stream = 16:6
= 8:3