Question

2) A car covers one-fourth of a distance at a speed of
100 km/hr, half of the remaining distance at a speed of
60 km/hr and the remaining distance at a speed of
100 km/hr. If the total time taken to complete the journey
is 10 hours, then what is the average speed of the car?​

Answer 1

Answer:

80 km/hr

Step-by-step explanation:

Let x be the distance

A car covers one-fourth of a distance at a speed of  100 km/hr

1/4x in 100 km/hr

half of the remaining distance at a speed of  60 km/hr

remaining 1-1/4=3/4

half of remaining 1/2*3/4=3/8x

remaining 3/8x at a speed of 100 km/hr

If the total time taken to complete the journey  is 10 hours

Total time taken 10hrs

Time=Distance/speed

10 hrs=(1/4x)/100+(3/8x)/60+(3/8x)/100

100=(1/40)x+(1/16)x+(3/80)x

100=2x+5x+3x/80  

x=800

average speed=total distance traveled/total time taken

                         =800/10

                         =80 km/hr