A vendor purchased 40 dozens bananas for Rs250. Out of these 30 bananas were rotten and could not be sold. At what rate per dozen should he sell the remaining bananas to make a profit of 20%.

CP=Rs.250

if the vendor wants a profit of 20% then the SP must be-

20/100*250=Rs.50

=Rs.250+Rs.50

=Rs.300

40 dozen bananas=Rs.250

480 bananas=Rs.250

bananas which can be sold=480-30=450

the vendor has to sell 450 bananas forRs.300 to get a profit of 20%

450 bananas=Rs.300

1 banana=Rs.0.6666666666666667

12 banana=Rs.8

therefore the vendor has to sell the bananas at Rs.8 per dozen to get a profit of 20 %