Question

(i) A car travels 50 km at xkm/h and then 80km at (x+10) km/h. Find an expression, in terms of x, for the total time taken, T hours. Give your answer as a single fraction, in its simplest form.

Answer 1

Answer:

Let the each half of the running time be t.

During first half time, speed of car is 80 km/h

Distance covered d

1

=80t km

During second half time, speed of car is 40 km/h

Distance covered d

2

=40t km

Total distance covered d=d

1

+d

2

=80t+40t=120t

Total time taken T=2t

Average speed v

avg

=

T

d

=

2t

120t

=60 km/hr