Dead-heat start in 1 km race: L runs 1 km in 10 min and M in 12 min. What start (in metres) can L give M in a 1 km race so that the finish is a dead heat?

Difficulty: Easy

Correct Answer: 1662/3 m

Explanation:

Introduction / Context:A “start” means the slower runner begins closer to the finish. For a dead heat, the slower runner’s actual running distance must match how far they would get in the faster runner’s finish time.

Given Data / Assumptions:

  • L = 1000 m in 10 min
  • M = 1000 m in 12 min
  • Race length = 1000 m

Concept / Approach:In L’s finish time (10 min), M would cover (1000 * 10/12) m. The start equals 1000 minus this distance.

Step-by-Step Solution:

M's distance in 10 min = 1000*(10/12) = 833 1/3 mRequired start = 1000 − 833 1/3 = 166 2/3 m

Verification / Alternative check:With this start, both finish together in 10 min (L’s time).

Why Other Options Are Wrong:Other values would not synchronize finishes.

Common Pitfalls:Using speed differences instead of proportionate distances in the common finish time.

Final Answer:1662/3 m

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