Question

Find the average speed of a bus if it moves from point A to B at a speed of 30 km/h and returns at a speed of 50 km/h

Answer 1

from a to b time taken is t1

and from b to a time taken is t2

distance d = time × speed

d = t1 × 30 = 30t1

d = t2 × 50 = 50t2

also , 30t1 = 50t2

t1 = 5/3 t2

total distance covered = 2d
total time = t1 + t2

so speed = dist /time

= d + d / t1 + t2

= 30t1 + 50t2 / t1 + t2

= (30 × 5/3 t2 + 50t2 ) / 5/3t2 + t2

= (100 t2) / 8t2/3

= 100 t2 ×3 / 8 t2

37.5 km / hr

Answer 2

Answer:

from a to b time taken is t1

and from b to a time taken is t2

distance d = time × speed

d = t1 × 30 = 30t1

d = t2 × 50 = 50t2

also , 30t1 = 50t2

t1 = 5/3 t2

total distance covered = 2d

total time = t1 + t2

so speed = dist /time

= d + d / t1 + t2

= 30t1 + 50t2 / t1 + t2

= (30 × 5/3 t2 + 50t2 ) / 5/3t2 + t2

= (100 t2) / 8t2/3

= 100 t2 ×3 / 8 t2

37.5 km / hr

Explanation: