Question

The mean of marks secured by 3 students in grade A of class XI is 83, that of 4 students of grade B is 76 and that of 5 students of grade C is 85. What will be the mean of marks of the students of three grades of Class XI?

• A. 80.5
• B. 81
• C. 80
• D. 81.5

Answer 1

Answer:

D. 81.5

To find the overall mean, use the weighted average formula:

Total students = (3 + 4 + 5 = 12)

Total marks:

• Grade A → $(3 \times 83 = 249)$

• Grade B → $(4 \times 76 = 304)$

• Grade C → $(5 \times 85 = 425)$

Sum of all marks = (249 + 304 + 425 = 978)

Now, overall mean:

$\text{Mean} = \frac{978}{12} = 81.5$