UP Police Constable Exam Model Paper 2

Given:
Required distance = 2d
Speed${}_1^{},{\mathrm{s}}_1=$ = 20 km/hr
Speed${}_2^{},{\mathrm{s}}_2$ = 30 km/hr
Total time taken = 12 hours
Formula used:
Speed = Distance/Time
Calculation
Let the total distance = 2d
Hence,
d/${\mathrm{s}}_1$ + d/${\mathrm{s}}_2$ = Total time taken
⇒ d/20 + d/30 = 12
⇒ (3d + 2d)/60 = 12
⇒ 5d = 720
⇒ d = 144
∴ Total distance = 2d = 2 × 144 = 288 km.