Question

a man covers first onefourth of a certain distance at at speed of 20km/h the next one fourth of the same distance at a speed of 40 km/h and next 1/4th at a speed of 60km/h and the remaining distance at a speed of 80km/h find his average speed in km/h for the entire journey

Answer 1

Explanation:

Letx consider, x= total distance covered by the car,

Letx consider, x= total distance covered by the car,Time taken to complete the half distance with velocity v=40km/h,

Letx consider, x= total distance covered by the car,Time taken to complete the half distance with velocity v=40km/h,t 1 = x/2×40 = x/80hr. . . . .(1)

The time taken to complete another half distance with velocity u=60km/h

t2= x/2×60=x/120 hr

The total time taken, t=t1+t2

+t2

+t2

+t2 t= x/80+ x/120= x/48hr

48hrThe average speed of the car,

v avg= x/x/48 =48km/h