Question

A car travels with a speed of 40km/h for 20 hours and them with the 60km/h for 2 hours find the average speed of the car²​

Answer 1

Answer:

Speed of car in first 15 minutes = 40 km/h

Distance covered = speed × Time taken

60 minutes = 1 hour

15 minutes =  

60

15

​  

 hour

Distance covered = 240×  

60

15

​  

=10km

Speed of car in next 15 minutes = 60 km/h

Distance covered = 60×  

60

15

​  

=15km

∴ Total distance covered = (10+15)km = 25 km

∴ 25 km is correct

Explanation:

Answer 2

✬ Average Speed = 41.81 km/h ✬

Explanation:

Given:

• A car travels 40 km/h for 20 hours.
• After that car travels 60 km/h for 2 hours.

To Find:

• What is the average speed of car?

Formula to be used:

• Distance = Speed $\times$ Time
• Average speed = Total Distance/Total time

Solution: Let distance covered by car be d¹ and d².

[ In first case ]

• Time¹ = 20 hours

➟ Distance¹ = 40 km/h $\times$ 20 hours = 800 km

[ In second case ]

• Time² = 2 hours

➟ Distance² = 60 km/h $\times$ 2 = 120 km

∴ Total distance covered by car = D¹ + D²

➱ (800 + 120) = 920 km

∴ Total time taken by car = t¹ + t²

➱ (20 + 2) = 22 hours

So,

$\implies{\rm }$ Average speed = 920/22

$\implies{\rm }$ Average speed = 41.81 km/h

Hence, the Average speed of car is 41.81 km/h.