Correct Answer - Option 3 : 2.75
Given:
Time for 44 km round trip = 12 hours.
Ratio of boat speed to stream speed = 3 : 1
Formula:
Speed = Distance/Time
Downstream speed = u + v
Upstream speed = u – v
u and v are speed of boat and stream respectively
Calculation:
Let speeds of boat and stream be 3x and x respectively.
44/(3x – x) + 44/(x + 3x) = 12
44/2x + 44/4x = 12
132/4x = 12
x = 2.75 km/hr
∴ The speed of stream is 2.75 km/h.