How many 4’s are there in the following which are preceded by 7 but NOT followed by 3? 5 9 3 2 1 7 4 2 6 9 7 4 6 1 3 2 8 7 4 1 3 8 3 2 5 6 7 4 3 9 5 8 2 0 1 8 7 4 6 3

The correct answer is A) Four. Scan the series for every 4, then check its left neighbour (must be 7) and its right neighbour (must not be 3). There are five 4s in the series. The 7-4 pairs are at positions 7, 12, 19, 28 and 38. The one at position 28 is followed by 3, so it is ruled out, leaving four.

• The 4 at position 7 is preceded by 7 and followed by 2. It counts.
• The 4 at position 12 is preceded by 7 and followed by 6. It counts.
• The 4 at position 19 is preceded by 7 and followed by 1. It counts.
• The 4 at position 28 is preceded by 7 but followed by 3. It is excluded.
• The 4 at position 38 is preceded by 7 and followed by 6. It counts.

The core concept is simple pattern scanning with a two-condition filter. Keep the 'preceded by' and 'followed by' conditions separate and check them one at a time. This kind of disciplined sequence work is what Prelims reasoning sections test, and it trains the same care needed for data-based questions in Mains.

Trap: Aspirants often count every 7-4 pair and forget the 'NOT followed by 3' condition, which gives Five (option D).