Question

The average of marks of 28 students in Mathematics was 50. Eight students left the school and then this average increased by 5. What is the average of marks obtained by the students who left the school ?

• A. 37.5
• B. 42.5
• C. 45
• D. 50.5

Answer 1

Answer: (A)

37.5

Total marks of 28 students in Mathematics = 28 x 50 = 1400
New number of students = 28 - 8 = 20
New average of marks in Mathematics = 50 + 5 = 55
$\therefore$ Total marks of 20 students in Mathematics = 20 x 55 = 1100
$\therefore$ Total marks of 8 students who left the school = 1400 - 1100 = 300
$\therefore$ Average marks of these 8 students = $\frac{300}{8}$ = 37.5