A boy ran a distance of 200m in 24s. His average speed was 8.3 ms^ -1 . Which of the following is correct…

Analyze the question: The statement uses three quantities: distance (200 m), time (24 s) and average speed (8.3 m/s). We need to classify each unit as fundamental (base) or derived, and as SI or not.

Concept:

• Fundamental (base) SI units include metre (m) for length, second (s) for time, kilogram (kg) for mass, and so on.
• Derived units are combinations of fundamental units, e.g. speed in m/s.

Solution:

1. Distance, 200 m: the metre is a fundamental unit.
2. Time, 24 s: the second is a fundamental unit.
3. Average speed, 8.3 m s⁻¹: this is length divided by time, so it is a derived unit.

Checking each option:

• A. All fundamental? No, since m s⁻¹ is derived.
• B. All derived? No, since m and s are fundamental.
• C. All except one are SI? No, all three units (m, s, m s⁻¹) are SI units.
• D. Two fundamental (m, s) and one derived (m s⁻¹)? Yes.
• E. None is SI? No, all are SI.

(Check: 200 ÷ 24 ≈ 8.3 m/s, so the data are consistent.)

Tip: In questions like this, list each quantity, write its unit, and ask whether it is a base unit (m, kg, s, A, K, mol, cd) or a combination of them. Any unit with a "per" (like m/s) is derived.