The cost of 3 pens and 5 pencils is Rs.200. Also the cost of one pen and one pencil is in the ratio of 5:1 respectively. What is the cost of one dozen pens?
Choose the correct choice from the following.
A) Rs.200	B) Rs.250	C) Rs.300	D) Rs.150	E) Rs. 600
Explanation:   Let the cost of one pen is ‘5x’ and pencil is ‘x’   3 X 5x + 5x = Rs.200   15x + 5x = Rs.200   X = 200/20= 
<gadget id="calculator">200/20</gadget>
<output>10</output>
10   :. Cost of 1 pen= 5x = 5 x 10 = 50   :. Cost of 12 pens, i.e. (one dozen) = 50 x 12 = Rs.600   Answer: Option Rs. 600
<result>E</result>
The cost of 3 pens and 5 pencils is Rs.200. Also the cost of one pen and one pencil is in the ratio of 5:1 respectively. What is the cost of one dozen pens?