Question

A class of 30 students appeared in a test. The average score of 12 students is 80, and that of the rest is 70. What is the average score of the class?

• A. 74
• B. 77
• C. 87
• D. 67

Answer 1

Answer:

A. 74

Total students (= 30)

• 12 students have an average score of 80.

• Remaining students (= 30 - 12 = 18) have an average score of 70.

  Total marks of first group

$12 \times 80 = 960$

Total marks of second group

$18 \times 70 = 1260$

Total marks of the class

$960 + 1260 = 2220$

Average score of the class

$\frac{2220}{30} = 74$

So, the average score of the class is:

$=\boxed{74}$