A trader buys 250 kg of potatoes at ₹16 per kg and pays ₹800 to have them brought to his shop. One-fifth of the stock is found spoiled and is thrown away. At what price per kg (in ₹) must he sell the rest to make a profit of 25% on his total outlay?

Outlay = $250\times 16+800=$ ₹4800, so he needs $4800\times 1.25$ = ₹6000. Only 200 kg is fit to sell, so the price must be 6000/200 = ₹30 per kg. (₹24 spreads the ₹6000 over the full 250 kg as though nothing had spoiled — it is also, by coincidence, the break-even price on 200 kg. ₹25 leaves the ₹800 freight out of the outlay, and ₹20 simply marks the ₹16 purchase rate up by 25%, recovering neither the freight nor the spoilage.)