Each of the letters in the word STAMINA is arranged in alphabetical order. How many letters are there in the English alphabetical series between the letter that is first from the left and the one that is fourth from the right in the new letter-cluster formed?

Correct — A.
Rule: sort the letters, find both positions, count the letters strictly between them.

STAMINA sorted: A A I M N S T, both As kept.
First from the left: A(1).
Fourth from the right: T, S, N, M(13).

Letters between A and M: B to L.
13 − 1 − 1 = 11 → option (a).

Why the others are wrong

• (b)
  12 — 12 is 13 − 1, the distance from A to M, which counts M itself. The letters strictly between are one fewer: B to L, 11.
• (c)
  13 — 13 is M's own position in the alphabet, not the count of letters between A and M. Take away A's position and one more: 13 − 1 − 1 = 11.
• (d)
  14 — 14 would need the second letter to be P(16), and STAMINA has no P. From A(1) to M(13), only 11 letters lie between.

These items have three steps: sort the word's letters alphabetically, locate the two letters by counting from the stated ends, then count the alphabet letters strictly between them.

Keep repeated letters when sorting. STAMINA has two As; here they sit at the left end and do not move M, but in other words a dropped duplicate shifts later positions. The count between positions p and q is q − p − 1.

Key facts

• Letters strictly between alphabet positions p and q: q − p − 1.
• A = 1, I = 9, M = 13, N = 14, S = 19, T = 20.
• STAMINA sorted alphabetically is A A I M N S T.

Common traps

• Counting q − p = 12 and forgetting that the letters strictly between are one fewer
• Answering with M's position, 13, instead of the count between

No directly related past PYQ was found.