Directions: Question is followed by two statements, I and II, giving certain…
2023
Directions: Question is followed by two statements, I and II, giving certain data.
What is the average weight of the class?
(i) The average weight of the boys is greater than the average weight of the girls.
(ii) The number of students in the class is 30 and their total weight is 1200 kg.
- A.
The question can be answered by using Statement I alone, but not by using Statement II alone.
- B.
The question can be answered by using Statement II alone, but not by using Statement I alone.
- C.
The question can be answered by using both the statements together, but cannot be answered by using either statement alone.
- D.
The question cannot be answered even by using both the statements together.
Attempted by 4 students.
Show answer & explanation
Correct answer: B
Concept: For any group, Average = Total sum of values ÷ Number of values. In a Data Sufficiency question you must test EACH statement entirely on its own first — a statement is sufficient only if, by itself, it fixes one definite numeric value; only when no single statement works alone do you check them together.
Application:
Statement I only compares the boys' and girls' average weights (one is greater) — it gives no actual weight figures and no counts, so it cannot fix any numeric average by itself.
Statement II directly gives the number of students (30) and their total weight (1200 kg).
Applying the average formula to Statement II alone: Average = 1200 ÷ 30 = 40 kg — a definite value, obtained without any input from Statement I.
Cross-check: Re-testing Statement I alone confirms a comparison carries no magnitude, so it can never yield a number; re-testing Statement II alone reproduces 1200 ÷ 30 = 40 kg independently of Statement I — confirming Statement II alone is sufficient while Statement I alone is not.
Therefore, the question can be answered by using Statement II alone, but not by using Statement I alone.