Question

Pupil's of 10th standard of a school had arranged for a function at a total cost of Rs.1,000 which was to be shared equally among them. Since 10 of them failed to join the function each of them had to pay Rs.5 more. Find the number of pupils in the class?

Answer 1

Let the number of pupil in the class be x
Amount = 1000

Cost each student had to pay = 1000/x

Since 10 students have failed to join ;

New amount = previous amount + 5

1000/(x-10) = (1000/x)+5

1000/(x-10) = (5x+1000)/x

1000x = 5x^2 +1000x -50x-10000

5x^2-50x-10000 = 0

x^2 -10x -2000 = 0

x^2 -50x +40x -2000 = 0

x (x-50) +40 (x-50) = 0

(x+40) (x-50) = 0

x = +50 & -40
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As the number of pupils can't be negative,
hence the number of pupils is 50