Question

In a hostel it takes ₹1800 to keep 50 children for 8 weeks . For what length of time did the cost of keeping 90 children amount to ₹21060?

Answer 1

Use the unitary method.
8 weeks = 8×7 days= 56 days.
To keep 1 child for 56 days, cost= 1800÷50 = Rs. 36

Therefore, to keep 1 child for 1 day, cost= 36/56 ...................{1}

Now, to keep 90 children for 1 day, cost= 90×36/56...............................{2}

Let the number of days be x.
Then,
21060= 90×36/56×x
21060/90 ×56/36 =x {now do the division and multiplication}
=364 = x

Hence 90 children can be kept for 364 days in the hostel for rupees 21060.
I hope this helps.