Correct Answer - Option 3 : B and C
Given:
Length of circular track = 700 meters
Speed of X = 72 km/hr
Speed of Y = 36 km/hr
Concept used:
To find the time taken to meet at starting point, take L.C.M of the time taken by persons
Calculation:
Speed of X in m/sec = 72 × (5/18) = 20 m/sec
Speed of Y in m/sec = 36 × (5/18) = 10 m/sec
⇒ Time taken by X to cover 700 meters = 700/20 = 35 sec
⇒ Time taken by Y to cover 700 meters = 700/10 = 70 sec
L.C.M of 70 & 35 = 70
B. L.C.M of 70 and 10
L.C.M of 70 and 10 = 70
B is correct
C. L.C.M of 70 and 35
L.C.M of 70 and 35 = 70
C is correct
∴ B and C are correct.