Question

a car travels 100 km at a speed of 60 km/h and returns with a speed of 40 km/h calculate speed for whole journey

Answer 1

@

Average speed = Total distance / Total time

=> 100+100 / t1 +t2

We know that time = d/s
=> t1 = 100/60 = 5/3
=> t2 = 100/40 = 5/2

Average speed = 200 / 5/2+5/3
=> 200 / (15+10)/6
=> 200 / 25/6
=> 200×6 / 25
=> 1200 / 25
=> 48 km/h

Average speed for whole journey = 48 km/h

@:-)

Answer 2

Answer:

Explanation:

Average speed = Total distance / Total time

=> 100+100 / t1 +t2

We know that time = d/s

=> t1 = 100/60 = 5/3

=> t2 = 100/40 = 5/2

Average speed = 200 / 5/2+5/3

=> 200 / (15+10)/6

=> 200 / 25/6

=> 200×6 / 25

=> 1200 / 25

=> 48 km/h

Average speed for whole journey = 48 km/h