Certain books are bought at prices ranging from Rs 400 to Rs 500 per book and are sold at prices ranging from Rs 500 to Rs 700 per book. Find the greatest possible profit that might be made in selling 10 books.

The greatest possible profit on 10 books is Rs 3000.

Maximum profit per book comes from the lowest cost and highest sale.

Lowest cost = Rs 400 and highest sale = Rs 700.

Profit per book = 700 - 400 = Rs 300.

For 10 books = 300 x 10 = Rs 3000.