Question

A car travels the first third of a distance with a speed of 10 kmph, the second third at 20 kmph and the last third at 60 kmph. What is its mean speed over the entire distance?

Answer 1

Hii friend,

# Answer- 16.36 km/h

# Explaination-
Suppose total distance traveled is L km.

During first 1/3rd, (s=L/3, v=10kmph)
t1 = s/v
t1 = L/(3×10)
t1 = L/30 hr

During middle 1/3rd, (s=L/3, v=20kmph)
t2 = s/v
t2 = L/(3×20)
t2 = L/60 hr

During last 1/3rd, (s=L/3, v=30kmph)
t3 = s/v
t3 = L/(3×30)
t3 = L/90 hr

Total time ,
t = t1+t2+t3
t = L/30+L/60+L/90
t = 11L/180 hr

Total distance = L km

So now, average velocity,
v = s/t
v = L/(11L/180)
v = 180/11
v = 16.36 km/h.

Average velocity over complete journey is 16.36 km/h.

Hope you got it...

Answer 2

Answer:

car travels the first third of a distance with a speed of 10 kmph, the second third at 20 kmph and the last third at 60 kmph. What is its mean speed over the entire distance?