Question

Choose the correct option for each of the following. 1. Acar travels with a uniform speed of 60 km/h. What would be the time taken by the car to travel a distance of 180 km? a (a) 1h (b) 2 h (c) 3 h (d) 4h 2. Average speed is calculated by (a) Total distance/total time (b) Total time/total distance (c) (Speed 1 + Speed 2)/2 (d) None of the above 3. A boy has to cover 20 km in 2 h. What should be his speed? (a) 10 km/h (b) 20 km/h (c) 1/10 km/h (d) 40 km/h​

Answer 1

Answer:

The correct option is D 180 km/h

Let the total distance be 2D

For first half distance D:

Time taken =DistanceAverage speed=D60

For the later half distance D, let the average speed be v

Time taken =Dv

For total journey:

Total distance=Average speed×Time ⇒2D=90×(D60+Dv)

On Solving, v=180 km/h