Question

5. A car moves with a speed of 30 km/h for half an hour, 25 km/h for one hour and 40 km/h for two<br />hours. Calculate the average speed of the car.​

Answer 1

Average speed = Total distance travelled ÷ Total time taken.

Traveling at 30 km/h for 1/2 hours = 15km. Traveling at 25 km/h for 1 hour = 25 km. Traveling at 40 km/h for 2 hours = 80km. Therefore, total distance traveled will be 15 km + 25 km + 80 km = 120 km.

Answer 2

Answer:

Explanation:

Solution,

Speed = 30 km/h

Time taken = 1/2 hour

We know that,

Distance = Speed × Time

Distance = 30 × 1/2

Distance, D₁ = 15 km

Now, Speed = 25 km/h

Time taken = 1 hour

Distance = 25 × 1

Distance, D₂ = 25 km

Speed = 40 km/h

Distance = 40 × 2

Distance, D₃ = 80 km

Total distance covered = D₁ + D₂ + D₃ = 15 + 25 + 80 = 120 km.

Total time taken = 1/2 + 1 + 2 = 3 hr 30 min = 7/2 hrs

Now, we know that,

Average speed = Total distance/Total time taken

⇒ Average speed = 120/7/2

⇒ Average speed = 120 × 2/7

⇒ Average speed = 34.28 km/h

Hence, the average speed of the car is 34.28 km/h.