SSC CGL 2025 Tier-I · 12 September 2025, Shift 2 · General Intelligence and Reasoning · Question 13 of 100

We transcribed this text from the pictures on a candidate's response sheet for this shift; the answer is the key SSC colour-marked on that sheet. Solution last reviewed 13 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. From 2025 the candidate response sheet prints every question and option as a picture, so the text here is transcribed from those pictures for this shift and checked against them independently; where the layout carries meaning, the picture is shown as well. Each answer is the key SSC colour-marked on that sheet. SSC released a tentative key for challenge and later its final one, both only to candidates behind a login, and the sheet does not say which of the two it carries. The solutions are written by UnlockIAS.

In a row of 50 books, Book A is 15th from left and Book B is 20th from right. How many books lie between them?

(a)17
(b)15
(c)12
(d)10

Answer

Why

Correct — B.
Rule: count both books from the same end, subtract, then take away 1.

B from the left = 50 − 20 + 1 = 31st
A from the left = 15th
Books between = 31 − 15 − 1 = 15 → option (b).

Check: A's 15 and B's 20 do not overlap (15 + 20 = 35), so 50 − 35 = 15 lie between.

Why the others are wrong

(a)
17 — 17 is 31 − 15 + 1, the count from A to B including both books. The question asks for the books between them, which leaves out A and B.
(c)
12 — 12 would put B 28th from the left, which is 23rd from the right, not 20th. With B 31st, positions 16 to 30 lie between: 15 books.
(d)
10 — 10 would need B to stand 26th from the left, which is 25th from the right. B is 20th from the right, so 31st from the left.

Concept

A row question gives two ranks from opposite ends. Convert one of them so both count from the same end: rank from the left = total − rank from the right + 1.

The books strictly between are then the difference minus 1. When the two stretches do not overlap, the same count comes out as total − (left rank + right rank): here 50 − 35 = 15.

Check the order first. B is 31st from the left and A is 15th, so B stands to the right of A and the two stretches do not overlap. If they overlapped, the count would work differently.

Key facts

Rank from the left = total − rank from the right + 1.
Number strictly between ranks p and q counted from the same end = q − p − 1.
When the two ranks do not overlap, the number between = total − (left rank + right rank).

Study next

Row problems where the two positions overlapFinding the total when both ranks and the number between are givenPositions after two people in a row swap places

Common traps

Counting from A to B inclusive and choosing 17
Forgetting the + 1 when converting B's rank to a rank from the left

15 Sep 2025, 16:00, Reasoning Q.14 sets a row of 60: Meena 25th from the left, Rupa 20th from the right. Rupa is 41st from the left, and 41 − 25 − 1 = 15 is keyed.

14 Sep 2025, 09:00, Reasoning Q.14 does it with 40 students, keyed 10.

Related PYQs

No directly related past PYQ was found.

Topic: Problem Solving — all 123 SSC CGL questions on it, every solved shift.