Multiple choice

The average marks obtained by 15 students including (x) are 70 and the average marks obtained by 14 students excluding (x) is 68. What is the marks obtained by (x)?

  1. 78

  2. 98

  3. 88

  4. 90

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total marks for 15 students = 15 × 70 = 1050. Total marks for 14 students (excluding x) = 14 × 68 = 952. Therefore, marks obtained by x = 1050 - 952 = 98. This is a direct application of the average formula where x's marks represent the difference between the group totals.