How many 2s in the given number series are immediately preceded by 9?
6, 5, 2, 2, 9, 2, 1, 6, 2, 2, 9, 2, 1, 2, 9, 9, 2, 9, 5, 9
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 3
Here a 2 is counted only when the number just before it is 9. Each 2 in the series is checked with its neighbours:
5, 2, 2 (3rd term): preceded by 5, not counted
2, 2, 9 (4th term): preceded by 2, not counted
9, 2, 1 (6th term): counted
6, 2, 2 (9th term): preceded by 6, not counted
2, 2, 9 (10th term): preceded by 2, not counted
9, 2, 1 (12th term): counted
1, 2, 9 (14th term): preceded by 1, not counted
9, 2, 9 (17th term): counted
So the count is three (3).