Two runners, A and B, start from the same point on a circular track of 400 m. They run in the same direction with speeds of 10 m/s and 7 m/s, respectively. How many times will they cross each other in 15 minutes?
Show answer & explanation
Correct answer: B
Explanation
Given:
Track length = 400 meters
A's speed = 10 m/s
B's speed = 7 m/s
Time = 15 minutes = 900 seconds
By formula:
Relative speed = 10 − 7 = 3 m/s
Relative distance in 900 seconds = 3 × 900 = 2700 meters
Distance to cross once = 400 meters
Number of crosses = 2700 / 400 = 6.75
Complete times = 6