Question

A hostel has food for 60 days if after 15 days 500 more students joined th hostel and the food lasted for 40days only. How many students were there in hostel

Answer 1

625

Explanation:

here we are in an inverse proportion situation :

As the number of days increases

when the number of students decreases and vice versa.

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Say n is the original number of students.

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After 15 days, the rest of food is enough for n students for 45 days,

or enough for n+500 students for 25 days.

Then

45n = 25×(n + 500)

Then

45n = 25n + 25×500

Then

45n - 25n = 25×500

Then

20n = 12500

Then

n = 12500÷20

= 625

and thus , there were 625 students in the hostel.