She bought 16 dozen ball pen
Loss for 16 dozen pen = SP of 8 ball pen
Let CP of each pen = Rs. x
CP of 16 dozen ball pen = 16 ×12 × x
= loss = 8 SP
= 16 ×12 × x = 16×12× SP = 8 SP
= 16 ×12 × x = 200 SP
= SP = \(\frac{192}{200}x\)
Loss% = \(\cfrac{x-\frac{192}{200}x}{x}\) = \(\frac{8}{2}\) = 4%
If CP of 16 dozen ball pen = Rs. 576
= 16 ×12 × x = 576
= x = \(\frac{576}{16\times 12}\)
Selling price of one pen = \(\frac{192}{200}x\)
Selling price of dozen pen = 12 x \(\frac{192}{200}\) x \(\frac{576}{16\times 12}\) = Rs. 34.56