Mathematical Reasoning
20 students are queuing for their favourite food. Andy is the third in the queue. Ashley is the fifth from th…
Question 1 · Multiple choice
Question
20 students are queuing for their favourite food. Andy is the third in the queue. Ashley is the fifth from the end of the queue. How many students are queuing between the two of them?
Options
- A.12
- B.13
- C.11
- D.14
- E.10
Correct answer
Explanation
Step 1: Find each person's position from the front
There are 20 students total.
-
Andy: 3rd from the front (position 3)
-
Ashley: 5th from the end → convert to position from front:
Position from front = Total − Position from end + 1 = 20 − 5 + 1 = position 16
Step 2: Visualise the queue
Front → 1 2 [3] 4 5 6 7 8 9 10 11 12 13 14 15 [16] 17 18 19 20 ← Back
Andy Ashley
←──────────── 12 students between ────────────→
Step 3: Count students between them
"Between" means not counting Andy or Ashley themselves.
Students between = (Ashley's position) − (Andy's position) − 1
= 16 − 3 − 1 = 12 students
Verify: Positions 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 → count them: 12 ✓
Answer: 12 students
| Option | Value | Why it is wrong |
|---|---|---|
| A | 12 | 16 − 3 − 1 = 12. ✓ |
| B | 13 | Forgot to subtract 1 for Andy himself. ✗ |
| C | 11 | Off-by-one error. ✗ |
| D | 14 | Miscalculated Ashley's position. ✗ |
| E | 10 | Used 15 − 3 − 2 incorrectly. ✗ |