A shopkeeper marks up his goods by 30% and then gives a discount of 10% on the marked price. Apart from this, he uses a faulty balance which reads 1 kg for 870 g. What is his net profit percentage?

34.48%

MP = 30% above CP

Discount% = 10%

Let CP of goods 1kg = Rs. 1000

Marked Price = Rs. 1300

Discount = 10% of MP = 10% × 1300 = Rs. 130

Selling Price = Rs. 1170

But he sold 870g instead of 1kg

SP for 870g = Rs. 1170

CP = Rs. 870

Now Profit%= ( 1170 - 870 ) × \(\frac{100}{870}\) = 34.48%