A trader sells his goods to a customer at a profit of y%. If he gives 900gm instead of 1 kg, then his overall profit will be 20%. Find the value of y.

4 8 12 25

8

Let the cost of 1000 gm = Rs. 100 SP of 1000 gm = (100+y) But he uses 900 gm instead of 1000 gm SP of 900 gm = (100+y) ∴ CP of 900 gm = 90 ATQ,        20 = \(\frac{100+y - 90}{90}\) × 100          y = 8