A man covers a distance of 40 km. He covers first 10 km at 10 km/h, second 10 km at 20 km/h, third 10 km at 30 km/h and last 10 km at 40 km/h. What is the average speed of man?
Answers
Answer:
19.2 km/hr
Step-by-step explanation:
A man covers a distance of 40km, he covers the first 10km at 10km/h, the second 10km at 20km/h, the third 10km at 30km/h and the last 10km at 40km/h. What is the average speed of the man?
C. S. Sharma
Answered September 22, 2019
Friends…!
In this type of problem, we have to calculate time taken at each stage then calculate the total time as well as total distance to find the average speed. Accordingly
We know that Speed = Distance/Time
Time = Distance / Speed
Time to cover first 10 km = 10 /10 hr = 1hr
Time to cover second 10km = 10 / 20 hr = 1/2hr
Time to cover third 10 km =10/30hr = 1/3hr
Time to cover fourth 10 km b=10/40hr =1/4hr
Total time to cover 40 km
= (1+ 1/2 + 1/3 + 1/4) hour
=12 + 6 + 4 + 3 / 12 hour
Total time = 25 /12 hour
Total Distance = 40 km
Average Speed = Total Distance / Total Time
40 / (25 /12) km/hour
40 × 12/25 km/hour
480/25 km/hour
96/5 km/hour
19.2 km/hour
Average speed = 19.2 km/hour
Answer average speed of the man is 19.2 km/hour