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Let the total number of students be x Average marks obtained by the students = 85 Total marks = 85x After correcting the quantitative mistakes the average decreased by (85 - 70) = 15 marks Total reduction = 15 × 100 = 1500 Now According to the Question, (85x - 1500)/x = 80 80x = 85x – 1500 x = 300 Total number of students = 300
Alternate method: By alligation method, Total number of students = 200+100 = 300
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