By selling 1 dozen ball pens, a shopkeeper earned the profit equal to the selling price of 4 ball pens. Find his profit percent.

50% 40% 33.3% 31.25%

50%

ATQ, ⇒ S.P. - C.P. = Profit ⇒ 12 S.P. - 12 C.P. = 4 S.P. ⇒ 8 S.P. = 12 C.P. ⇒ S.P. : C.P. = 3 : 2 ⇒ Profit = 1R ⇒ Profit % = \(\frac{1}{2}\) × 100 = 50%