UP Police Constable Exam Model Paper 1

Given
Distance covers in downstream = 96 km
Time to cover downstream distance = 12 hours
Distance covers in upstream = (1/8) of 96
Time taken to cover upstream distance = 4 hours
Formula used
Speed = Distance/Time
Speed of stream = (Downstream speed - Upstream speed)/2
Calculation
Downstream speed $\left({\mathrm{D}}_{\mathrm{s}}\right)$ = 96/12
⇒ 8 km/h
Upstream speed $\left({\mathrm{U}}_{\mathrm{s}}\right)$ = [96 × (1/8)]/4
⇒ 12/4
⇒ 3 km/h
Speed of the stream = (8 - 3)/2
⇒ 5/2
⇒ 2.5 km/h
∴ Speed of stream is 2.5 km/h.