Question

a non-stop bus goes one station to another station with a speed of 54 km h-1.the same bus returns from the second station to the first station with a spees of 36km h-1.find average speed of the bus for the entire journey.

Answer 1

Hey Friend ☺

Speed ( 1 ) = 54 km/h

Speed ( 2 ) = 36 km/h

Average speed = speed ( 1 ) + speed ( 2 )/2

= 54 + 36/2

= 90/2

= 45 km/h

So the average speed of journey is 45 km/h

Hope it helps you ..!!

✌

Answer 2

Let the total distance covered by that bust from station A to station B = x m

Speed while travelling from Station A to B = 54km/h = 15m/s

Distance = x m

time taken = distance / speed = x/15

Speed While returning = 36km/h = 10m/s

As distance is going to be same from station A to B.

So distance = x m.

time taken = x/10

Average speed = total distance/ total time taken
$= \frac{2x}{ \frac{x}{15} + \frac{x}{10} } \\ \\ = \frac{2x}{ \frac{2x + 3x}{30} } \\ = \frac{(2x)(30)}{5x} \\ = \frac{60}{5} \\ = 12$
Therefore,
the average speed of the given body becomes 12m/s.