Question

2 3 7 4 3 2 1 5 7 3 2 7 1 0 9 8 7 5 4 7 2 3 Find the number of 7 in the given series that are followed by an even number but are not preceded by a prime number?

Accepted Answer

A. We look for pattern: [Non-Prime Number] - 7 - [Even Number]. Let's check all 7s in the sequence: 1. ...3 7 4... : Preceded by 3 (prime) - No. 2. ...5 7 3... : Followed by 3 (odd) - No. 3. ...2 7 1... : Followed by 1 (odd) - No. 4. ...8 7 5... : Followed by 5 (odd) - No. 5. ...4 7 2... : Preceded by 4 (non-prime) and followed by 2 (even) - YES! Total count = 1.

Number sequence conditions

Explanation

Practise this under exam conditions