A shopkeeper has 11 books of same cost price. He sells the first book at certain price, then he sells second book at a price which is ₹ 1 less than the selling price of first book and then he sells third book at a price which is ₹1 less than the selling price of second book. Following this pattern, he sold all 11 books. If he sells sixth book at its cost price. Find the overall percent profit or loss on selling all 11 books. 

If the cost of pins reduces by Rs . 4 per dozen, 12 more pins can be purchased for Rs. 48. The cost of pins per dozen after reduction is: 

Sandeep buys an old scooter for Rs.4700 and spends Rs.800 on its repairs. If he sells to its Rajesh for Rs.5800, then his gain percent will be:

If the profit on selling an article for Rs. 579 is the same as the loss on selling it for Rs. 337, then find the profit percent if its selling price is Rs. 687.

By selling an article for Rs. 320, a man incurs a loss of 20%, what should be the selling price of an article to gain 30%?

A starts a business, after 6 months B also join him with Rs.4500 and after 2 months of B’s joining C also join them with Rs.4500. If A gets approx. Rs 4900 out of total annual profit of Rs. 10,000 then find the approximate value of initial investment of A.