A person travels two-fifth of a distance at a speed of 40km/h and the remaining at a speed of 60km/h. What is his average speed (in km/h) in the entire journey?
- A40
- B48
- C60
- D50
Solution & Step-by-step Explanation
Let the total distance be D=500km (chosen for easy calculation as it is a multiple of 5).
Distance travelled at 40km/h is
5
2
×500=200km.
Remaining distance travelled at 60km/h is 500−200=300km.
Now, let's find the total time taken (T):
T
1
=
40
200
=5hours
T
2
=
60
300
=5hours
Total Time (T)=5+5=10hours
The average speed is given by:
Average Speed=
Total Time
Total Distance
=
10
500
=50km/h
Distance travelled at 40km/h is
5
2
×500=200km.
Remaining distance travelled at 60km/h is 500−200=300km.
Now, let's find the total time taken (T):
T
1
=
40
200
=5hours
T
2
=
60
300
=5hours
Total Time (T)=5+5=10hours
The average speed is given by:
Average Speed=
Total Time
Total Distance
=
10
500
=50km/h