DRDO Multi tasking staff Model paper 2

As per the given data,
Distance travelled in the first one hour = (40 × 1) = 40 km
Distance travelled in the next one hour = (50 × 1) = 50 km
Distance travelled in the next one hour = (60 × 1) = 60 km
Distance travelled in the next one hour = (70 × 1) = 70 km
Remaining distance = 240 – (40 + 50 + 60 + 70) = 240 – 220 = 20 km
Speed in 5th hour = 80 km /hr
Time taken to cover 20 km = (20/80) = 1/4 hours = 15 min
∴ Total time taken = 4 hours 15 min