Averages — Data Correction
Question
The class average x in a test increases by 4 when the score of a student is rectified, whose corrected score is 100 instead of 0. Later, the score of another student was found to have been recorded as 81 in place of 56. If there are no other corrections and the final corrected average is y, then y-x is
Options
2
3
5
6
Explanation
Let n be the total number of students in the class.
100/n = 4 \implies n = 25 students
y - x = 75/n = 75/25 = 3
Answer: (b).
Question details
Year
2026
Paper
CSAT
Question
Q5
Section
Quantitative Aptitude
Sub-topic
Averages
Type
Arithmetic Problem
Difficulty
Medium
Source hint
Standard averages — net change correction framework
Same sub-topic — other years
Averages has appeared in multiple CSAT papers:
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Evaluating data sufficiency to find the average of a specific subset
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Calculating the new average after altering specific terms in a set
Q80
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