By selling 99 pens, a trader gains the cost of 33 pens. Find his gain percentage?  Choose the correct choice from the following choices:
A) 33 1/3% B) 33 1/9% C) 33 9/3% D) 32 1/3% E) 33 1/2%
Let the CP of each pen be Rs. 1.   CP of 99 pens = Rs. 99   Profit = Cost of 33 pens = Rs. 33   Profit% = 33/99 * 100 = 33 1/3%   33 1/3%nswer: 33 1/3%
<result>A</result>
By selling 99 pens, a trader gains the cost of 33 pens. Find his gain percentage?