In an examination, the average mark of 60 girls is 15 and 40 boys is 30. The average marks of the group in which the boys and girls are taken together are:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. 21.
We know that,
Average = Sum of observations/Number of observations
Now,
Average marks of 60 girls = 15
Total Marks of 60 girls = 15 × 60 = 900
Average marks of 40 boys = 30
Total Marks of 40 boys = 30 × 40 = 1200
Total Marks of boys and girls combined = 1200 + 900 = 2100
Average marks of the group in which boys and girls are taken together
⇒ 2100/(60 + 40) = 2100/100 = 21