1 km race timing from lead: In a 1 km race, A beats B by 25 m or 5 s. Determine the time A takes to finish the 1 km course.

Introduction / Context:This is a standard race problem where a distance lead is also given as a time lead. We use B’s speed deduced from “25 m in 5 s” and then compute A’s finish time.

Given Data / Assumptions:

• Total distance = 1000 m
• Lead at finish = 25 m = 5 s for B

Concept / Approach:When A finishes, B is at 975 m. The shared race time equals the time B takes to cover 975 m at B’s computed speed.

Step-by-Step Solution:

Verification / Alternative check:In 195 s, B would need 25 m more (5 s) to finish; consistent with the statement.

Why Other Options Are Wrong:Other times do not produce a 25 m (5 s) shortfall for B at A’s finish.

Common Pitfalls:Using 1000 m for B instead of 975 m for the common time reference.

Final Answer:3 minutes 15 seconds