Question

A man covers a distance of 40km.He covers first 10km at 10km/h, second 10 km at 20km/h, third f okmat 30km/h and last 10km at 40km/h. What is the average speed of man?

Answer 1

Answer:

19.2 kmph

Step-by-step explanation:

Time = Distance / Speed

Time taken in each 10 km is

t1 = 10/10 = 1 hr

t2 = 10/20 = 0.5 hr

t3 = 10/30 = 1/3 hr

t4 = 10/40 = 0.25 hr

Average speed = Total Distance / Total time

= 40 km / (1 hr + 0.5 hr + 1/3 hr + 0.25 hr)

= 40 km / (1.75 hr + 1/3 hr)

= 40 km / [(5.25 hr + 1 hr)/3]

= 120 km / 6.25 hr

= 19.2 kmph