Question

1. A car has to cover the distance 60 km. If half of the total time
it travels with speed 80 kmh and in rest half time its speed
becomes 40 kmh, the average speed of car will be
(a) 60 kmh
(b) 80kmh
(c) 120kmh
(d) 180kmh​

Answer 1

Answer:

Explanation:

The problem can be solved by two methods

Method 1 :

Vav = 80 + 40 / 2

= 120/2

= 60 km /h

Method 2 :

Let the half time intervals be t

Therefore 60 = 80t + 40t

t=1/2

total time = 1/2*2 = 1hr

vav = Total distance / Total time

= 60 / 1

= 60 km/h