The average marks obtained by a group of 25 students was 24 . One student left the group as a result of which the average of the remaining students ro - Quantitative Aptitude MCQ UP Police Constable 2026 | ExamTest.live

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The average marks obtained by a group of 25 students was 24 . One student left the group as a result of which the average of the remaining students rose to 25 . But another student came in as a result of which the average marks of the group dropped a bit and became 24.8 . What was the average marks obtained by the student who left and the one who joined later?

Solution & Step-by-step Explanation

Step 1: Total marks of initial 25 students Total marks = 25 \times 24 = 600 Step 2: Marks of the student who left When 1 student left, 24 students remained and the average became 25 . Total marks of remaining 24 students = 24 \times 25 = 600 Marks of the student who left = 600 - 600 = 0 Step 3: Marks of the student who joined When a new student joined, the total number of students became 25 again, and the average became 24.8 . New total marks of 25 students = 25 \times 24.8 = 620 Marks of the student who joined = 620 - 600 = 20 Step 4: Average marks of these two students Average = \frac{Marks of student who left + Marks of student who joined}{2} Average = \frac{0 + 20}{2} = 10

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The average marks obtained by a group of 25 students was 24 . One student left the group as a result of which the average of the remaining students rose to 25 . But another student came in as a result of which the average marks of the group dropped a bit and became 24.8 . What was the average marks obtained by the student who left and the one who joined later?

10

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20

25

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