Difficulty: Medium
Correct Answer: 75 m
Explanation:
Introduction / Context:
The original text had a likely typo (“1% times”). By the Recovery-First Policy we minimally repair to a standard form: A runs 1 2/3 times as fast as B. With a 30 m head start to B, find the race distance so they tie.
Given Data / Assumptions (after minimal repair):
Concept / Approach:
Equalize times: D / v_A = (D − 30) / v_B. Solve for D with v_A/v_B = 5/3.
Step-by-Step Solution:
Verification / Alternative check:
Times equal: 75/(5k) = 45/(3k) = 15/k.
Why Other Options Are Wrong:
They do not satisfy the time equality for ratio 5:3 with a 30 m head start.
Common Pitfalls:
Using speed difference instead of ratio, or forgetting to subtract the head start from B’s distance.
Final Answer:
75 m
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