Correct Answer - Option 2 : 40
Given :
The person traveled 60 km and returned to the same point
Time taken for return journey = 1/2 Hr + Time taken for outward journey
Speed during return journey = Speed during the outward journey - 10 km/h
Formula used :
Speed = Distance/Time
Calculation :
Let the Speed of outward journey be S1 and speed for return journey be S2
Also, Let the time taken for outward journey be T1 and time taken for return journey be T2
According to question,
S1 = 60/ T1
⇒ T1 = 60/S1 ----(1)
Also, from given information in question
T1 + 1/2 = T2 ----(2)
S2 = S1 - 10 ----(3)
For return journey,
T2 = 60 / S2
From Eq (2) and (3)
⇒ T1 + 1/2 = 60 / (S1 - 10)
⇒ (60/S1) +1/2 = 60 / (S1 - 10)
⇒ \( {600 \over (S1-10)S1} = {1\over2}\)
⇒ S1 (S1 - 10) = 1200
⇒ S1 = 40
∴ Speed of the person during outward journey is 40 km/h