A pupil's marks were wrongly entered as 83 instead of 63. Due to that the average marks for the class got increased by half (1/2). The number of pupils in the class is:
Aptitude
Average
Difficulty: Easy
Choose an option
Answer
Correct Answer: 40
Explanation
Problem Restatement
One mark was overstated by 20 points (83 instead of 63). This increased the average by 0.5. Find the class size.
Concept / Approach
Average increase = (Total error) ÷ (Number of students).
Step-by-step calculation
Total error = 83 − 63 = 20Let number of students be nIncrease in average = 0.5 = 20 ÷ n → n = 20 ÷ 0.5 = 40
Final Answer
Number of students in the class = 40.