Another chained advantage check: In a 600 m race, A beats B by 60 m. In a 500 m race, B beats C by 50 m. By how many metres will A beat C in a 400 m race?

Introduction / Context:
Identical to the previous setup; we apply speed ratios derived from given metre advantages and scale to the new race length.

Given Data / Assumptions:
As above: vA/vB = 10/9 and vB/vC = 10/9, hence vA/vC = 100/81; uniform speeds.

Concept / Approach:
Compute C's distance when A completes 400 m, then subtract from 400 m to obtain the margin.

Step-by-Step Solution:

Verification / Alternative check:
Proportional checks confirm 76 m.

Why Other Options Are Wrong:
Numbers not consistent with 100/81 ratio.

Common Pitfalls:
Using arithmetic differences instead of ratios across race lengths.

Final Answer:
76 m