Raghu bought 4 dozen oranges at Rs 12 per dozen and 2 dozen oranges at Rs 16 per dozen. He soldthem all to earn 20% profit. At what price per dozen did he sell the oranges ?

A. 14.4   
B. 16.8
C. 16   
D. 19.2
Answer:     C

Explanation:   

Total CP = (12*4 + 16 *2) = 80
SP of 6 dozen oranges = [(120/100 )* 80)] = 96
sell price per dozen =16