Correct Answer - Option 2 : 102 km
Given:
Initial speed of bus = 21 km/hr
Speed increases by 3 km/hr every hour
Time = 4 hours
Calculation:
Speed in 1st hour = 21 km/hr
Speed in 2nd hour = 24 km/hr
Speed in 3rd hour = 27 km/hr
Speed in 4th hour = 30 km/hr
Total distance covered in 4 hours = (21 + 24 + 27 + 30) km
∴ Total distance traveled by bus in 4 hours is 102 km