Correct Answer - Option 1 : 30 km
Given:
Speed of a boat in still water = 10 km/hr
Speed of stream = 2 km/hr
Concept used:
Downstream speed = Speed of a boat in still water + Speed of stream
Calculation:
Downstream speed = 10 + 2 = 12 km/hr
In 1-hour boat travels = 12 km
Then, in 2.5 hours boat will travel = 2.5 × 12 = 30 km
∴ The boat will travel 30 km downstream.