Question

Kivand and Dinesh travel a distance of 60 km such that the speed of Kivand is faster than Dinesh. The sum of their speeds is 80 km/h and the total time taken by both is 3 hours 12 minutes. Find the speed of Kivand?
1. 40 km/h
2. 30 km/h
3. 50 km/h
4. 45 km/h

Answer 1

Correct Answer - Option 3 : 50 km/h

Given:

Distance travelled = 60 km

Kivand faster than Dinesh

Sum of speeds of Kivand and Dinesh = 80 km/hr

Total time taken by both = 3 hours 12 min

Concept used:

Speed = distance /time

Calculation:

Let the speed of Kivand be K km/hr and Dinesh be D km/hr

Then ,sum of speeds = K + D = 80 km/hr       ----(1)

Total time = 60/K + 60/D = 3 + (12/60) hours

60/K + 60/D = 16/5      ----(2)

Let us use options along with (1) and (2) to arrive at the solution.

option 1 not possible as it is said that Kivand is faster than Dinesh.

Option 2 not possible as when K = 30 km/hr then D = 80 - 30 = 50 km/hr. Here also, K not greater than D

Option 3, K = 50 km/hr then, D = 80 - 50 = 30 km/hr

Applying these values in (2), the equation becomes, 60/50 + 60/30 = 6/5 + 2 = 16/5 hours

∴ We can conclude that speed of Kivand is 50 km/hr.