Question

8. A man covers half of his journey at 6 km/h and the
remaining half at 3 km/h. His average speed is
(a) 4.5 km/h
(b) 3 km/h
(4 km/h
(d) 9 km/h​

Answer 1

Answer:

Step-by-step explanation:

Let the total distance = x km.

First half is covered with a speed of 50 km/h.

`therefore` Time taken to cover first half of the distance `(t_(1))=(x/2)/50=x/100km`

Second half is covered with a speed of 40 km/h.

`therefore` Time taken to cover second half of the distance `(t_(2))=(x/2)/40=x/80km`

Total time = `t_(1)+t_(2)=x/100+x/80=(9x)/400`

Average speed of the car = `("Total distance")/"Time"=x/((9x)/(400))=400/9=44.44km//h`

Answer 2

Answer:

d) 4km/hr

Step-by-step explanation:

V1 = 6km/hr

V2= 3km/hr

S1 = S2 (where, S = distance)

we know, AVG. Speed = 2(V1 × V2)/V1 + V2

=2(18)/9

=4km/hr