A train runs at 200 km/h. Convert this speed to metres per second (m/s).

Introduction / Context:
Unit conversion between km/h and m/s is routine in motion problems. The factor is 1000/3600 = 5/18 to go from km/h to m/s. Accuracy to two decimal places is commonly acceptable for train-speed conversions in aptitude questions.

Given Data / Assumptions:

• Speed = 200 km/h.
• 1 km = 1000 m; 1 h = 3600 s.

Concept / Approach:
Use v(m/s) = v(km/h) * (1000/3600) = v(km/h) * (5/18). Keep sufficient decimal precision when required by options.

Step-by-Step Solution:

Verification / Alternative check:
Reverse conversion: 55.55 * (18/5) ≈ 199.98 km/h ≈ 200 km/h (rounding).

Why Other Options Are Wrong:
50 or 48 m/s are too low; 66.66 m/s would correspond to ~240 km/h, not 200 km/h.

Common Pitfalls:
Using 18/5 instead of 5/18 when converting km/h to m/s; truncation rather than rounding.

Final Answer:
55.55 m/sec