Question

A class of 25 students took an English test. 15 students had an average score of 80. The other students had an average score of 60. What is the average score of the whole class?

• A. 62
• B. 72
• C. 65
• D. 75

Hint:

Calculate weighted averages by multiplying subgroup averages by their sizes, summing, and dividing by total group size.

Answer 1

The Correct Option is B

Calculate the total scores of each group: \[ \text{Group 1 (15 students)}: 15 \times 80 = 1200 \] \[ \text{Group 2 (10 students)}: 10 \times 60 = 600 \] Total score for all students: \[ 1200 + 600 = 1800 \] Total number of students: 25. Average score of whole class: \[ \frac{1800}{25} = 72. \] This weighted average reflects the contribution of each subgroup's performance to the overall average.