In an examination, the average marks of the entire class was 70. If average marks scored by 10% of the students was 95 and average marks scored by other 20% of the students was 20, then what was the average marks of the remaining students of the class? (correct to one decimal place)
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 80.7%
The total marks of the class equal the sum of the totals of its groups. Assuming the class to have 100 students, the three groups have 10, 20 and 70 students.
Total of the class \(=100\times70=7000\)
10 students at 95: \(10\times95=950\)
20 students at 20: \(20\times20=400\)
Total of the remaining 70 students \(=7000-950-400=5650\)
Their average \(=5650\div70=80.71\ldots\approx80.7\)