Question

a car completed a certain journey in 8 hours. it covers half the distance at 40km per hour and the rest at 60km per hour. the length of the journey is​

Answer 1

Let the total distance covered be x km.

speed for half of the journey (x/2 km)

= 40 km/hr.

so, time taken = d/s

or, time taken= x/2/40

or, time taken = x/80hrs. (I)

again in 2nd case,

speed for rest of the journey (x/2km)

= 60 km/hr

time taken = x/2/60

or, t = x/ 120 hrs. (ii)

total time taken to cover the distance

= 8 hrs ( given)

equating both the equations

8 = x/80+x/120

or, 8 = 5x/240

or, 5x= 240×8

or, x = 240×8/5 = 384km.

therefore the required distance

= 384kms.