Key Concept: Remainders & Divisibility (Data Sufficiency)
The common trap here is jumping straight to testing numbers without first setting up the remainder constraints systematically. Let me show you the clean approach.
What the question tells us:
Number of applicants N satisfies:
— N ≡ 2 (mod 6), meaning N leaves remainder 2 when divided by 6
— 40 < N < 70
Step 1 — List all values in range satisfying the given condition.
Multiples of 6 between 40 and 70: 42, 48, 54, 60, 66
Add 2 to each: 44, 50, 56, 62, 68
These are your only candidates. Write them down — this is your working set.
Step 2 — Test Statement (1): "If sorted into groups of 5, none left over" → N ≡ 0 (mod 5)
From {44, 50, 56, 62, 68}, which are divisible by 5?
Only 50. Statement (1) alone gives a unique answer. ✅ Sufficient.
Step 3 — Test Statement (2): "If sorted into groups of 7, remainder is 1" → N ≡ 1 (mod 7)
Check each candidate:
44 ÷ 7 = 6 remainder 2 ✗
50 ÷ 7 = 7 remainder 1 ✓
56 ÷ 7 = 8 remainder 0 ✗
62 ÷ 7 = 8 remainder 6 ✗
68 ÷ 7 = 9 remainder 5 ✗
Only 50 works. Statement (2) alone also gives a unique answer. ✅ Sufficient.
Answer: D — each statement alone is sufficient.
The trap to avoid: Some students skip the Step 1 enumeration and try to evaluate the statements in isolation from scratch — that leads to messy algebra and mistakes. Whenever DS gives you a bounded range, your first move should always be to write out the complete candidate list from the original constraint, then filter with each statement.
Takeaway: In DS Remainders questions with a finite range, enumerate all valid candidates first — then each statement becomes a simple filter test.