How many 4s in the given number series are immediately preceded by 1?
1, 4, 3, 4, 1, 4, 2, 1, 1, 4, 4, 5, 1, 2, 4, 3, 1, 2, 4, 1
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 3
Here a 4 is counted only when the number just before it is 1. Each 4 in the series is checked with its neighbours:
1, 4, 3 (2nd term): counted
3, 4, 1 (4th term): preceded by 3, not counted
1, 4, 2 (6th term): counted
1, 4, 4 (10th term): counted
4, 4, 5 (11th term): preceded by 4, not counted
2, 4, 3 (15th term): preceded by 2, not counted
2, 4, 1 (19th term): preceded by 2, not counted
So the count is three (3).