A trader marked his goods at 20% above the cost price. He sold half the stock at the marked price,one quarter at a discount of 20% on the marked price and the rest at a discount of 40% on the marked price. His total gain is -

Explanation:-

Let C.P. of whole stock = Rs. 100
Then,
Marked price of whole stock = Rs. 120 $$\eqalign{ & {\text{M}}{\text{.P}}{\text{. of }}\frac{1}{2}{\text{ stock}} \cr & {\text{ = Rs}}{\text{. 60,}} \cr & {\text{M}}{\text{.P}}{\text{. of }}\frac{1}{4}{\text{ stock}} \cr & {\text{ = Rs}}{\text{. 30}} \cr}$$ ∴ Total S.P.
= Rs. [60 + (80% of 30) + (60% of 30)]
= Rs. (60 + 24 + 18) = Rs. 102
Hence, gain% = (102 - 100)% = 2%