A shopkeeper marks his goods 40% above their cost price. He sells 60% of the goods at the marked price and the remaining at 65% discount on the marked price. His gain/loss in the whole transaction is:

Let the total number of goods be 100 and the Cost Price (CP) of each item be Rs. 1.
Total CP=100×1=Rs. 100
The Marked Price (MP) of each item is 40% above CP:

MP=1×1.40=Rs. 1.40
Now, let's look at the sales structure:

60% of the goods are sold at the marked price:

Quantity=60
Selling Price (SP)
1
​
=60×1.40=Rs. 84
The remaining 40% of the goods are sold at a 65% discount on the marked price:

Quantity=40
Discounted SP per item=1.40×(1−
100
65
​
)=1.40×0.35=Rs. 0.49
Selling Price (SP)
2
​
=40×0.49=Rs. 19.60
Total Selling Price (Total SP):

Total SP=SP
1
​
+SP
2
​
=84+19.60=Rs. 103.60
Overall calculation:

Total SP>Total CP⟹Gain
Gain Amount=103.60−100=Rs. 3.60
Gain Percentage=(
100
3.60
​
)×100%=3.6%