Marks of a student were wrongly entered as 83 instead of 63 . Due to that the…
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Marks of a student were wrongly entered as 83 instead of 63 . Due to that the average marks for the class got increased by 0.5 then the number of students in the class is
Answer: C. 40 — Let n be the number of pupils in the class. The mistaken entry changes a pupil's mark from 63 to 83, increasing the total marks by 83 − 63 = 20. This…
- A.
10
- B.
20
- C.
40
- D.
73
Attempted by 26 students.
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Correct answer: C
Let n be the number of pupils in the class.
The mistaken entry changes a pupil's mark from 63 to 83, increasing the total marks by 83 − 63 = 20.
This increases the class average by (increase in total)/n = 20/n, and we are told the average increased by 1/2.
Set up the equation: 20/n = 1/2.
Solve for n: n = 20 ÷ (1/2) = 20 × 2 = 40.
Therefore the number of pupils in the class is 40.