A motorcycle is moving at the speed of 25 km/hr and its speed is increased by 7 km/hr at the end of each hour. How much time it will take to cover a distance of 225 km?

Given, Total distance = 225 km
Distance travelled in every hour will be equal to the speed.
Distance travelled in 1st hour = 25 km
Distance travelled in 2nd hour = 32 km (Speed increased by 7 km/hour)
Distance travelled in 3rd hour = 39 km
Distance travelled in 4th hour = 46 km
Distance travelled in 5th hour = 53 km
Total distance travelled in 5 hours = 25+32+39+46+53 = 195 km
Remaining distance = 225-195 = 30 km
Speed for 6th hour will be 53+7 = 60 km/hr
Hence, 30 km can be travelled in 0.5 hours.
Therefore, 225 km distance will be travelled in 5.5 hours = $$\dfrac{11}{2} hr$$