Question

In a class the average marks obtained in a science test by a group of 12 students is 70, by another group of 15 students is 85 and that by another group of 18 students is 90. Find the average marks of all the students.

• A. 84.5
• B. 82.5
• C. 83
• D. 86

Answer 1

Answer:

C. 83

Step 1: Calculate Total Students

• Group 1: 12 students.

• Group 2: 15 students.

• Group 3: 18 students.

• Total count: 45 students.

Step 2: Calculate Total Marks

• Group 1: 12 × 70 = 840.

• Group 2: 15 × 85 = 1,275.

• Group 3: 18 × 90 = 1,620.

• Combined sum: 3,735 marks.

Step 3: Find Combined Average

• Formula: Total Marks ÷ Total Students.

• Calculation: 3,735 ÷ 45.

• Result: 83.