Winning margin from 100 m times: A runs 100 m in 27 s and B in 30 s. By how many metres does A beat B?

Introduction / Context:
Compute the distance B covers in the time A finishes; the difference from 100 m is A’s winning margin.

Given Data / Assumptions:

• A's time = 27 s
• B's 100 m time = 30 s

Concept / Approach:
Distance covered by B in 27 s equals (27/30)*100. Subtract from 100 to get the margin.

Step-by-Step Solution:

Verification / Alternative check:
Speed method: v_B = 100/30 m/s, margin over 27 s = (100/27 − 100/30)*27 = 10 m.

Why Other Options Are Wrong:
They do not match B’s progress in 27 s.

Common Pitfalls:
Using time difference (3 s) as distance; times must be converted via speed.

Final Answer:
10 m