Vinay bought 100 pens (all at same cost price). He sold 40 pens at a profit of 20 percent, 20 pens at a profit of 40 percent and the remaining at the cost price. If he had sold all at a profit of 20 percent, then he would have got Rs. 160 more. What is the cost price of each pen?

Correct option is D

Given:

Total pen = 100

40 pens = 20% Profit

20 pens = 40% Profit

40 pens = Cost Price

100 Pens = 20 % Profit = Rs. 160 more

Formula used:

Profit % = (Profit/Cost Price) x 100

Profit = Selling Price (SP) - Cost Price (CP)

Solution:

SP for 40 pens = 40 × 1.2 = 48

SP for 20 pens = 20 × 1.4 = 28

SP for remaining pens = 40

Total selling price = 48 + 28 + 40 = 116

Now, 

On selling all pens (100 pens) at 20% profit

Selling price = 100 × 1.2 = 120

Here,

Difference = 120 - 116 = 4 units

4 units = 160

1 unit = 40

Thus, the cost price of 1 pen = Rs. 40

∴ The correct answer is option (d).