Kunal electronic services assemble computers. Over a period of time the engineers made the following observation regarding the two vital components - the USB port and CD drive. The probability that USB port is defective is 0.1, that both the USB port and CD drive are defective is 0.02, while the probability that only the CD drive is defective is 0.03 . The probability that the USB port is defective when the CD drive has been found to be defective is?
Choose one:
A) 0.2 B) 0.3 C) 0.25 D) 0.4 E) 0.6
Explanation :   USB Defective	USB OK	Total   CD Defective	0.02	0.03	(0.05)   CD OK	(0.08)	(0.87)   (0.95)   Total	0.1	(0.9)   The figures enclosed in brackets follow as conclusions. The probability that USB part is defective, when the C0.4 drive is found to be defective is 0.02/0.02+0.03 = 2/5= 
<gadget id="calculator">2/5</gadget>
<output>2/5 = around 0.4</output>
0.40   Answer : 0.4
<result>D</result>
Kunal electronic services assemble computers. Over a period of time the engineers made the following observation regarding the two vital components - the USB port and CD drive. The probability that USB port is defective is 0.1, that both the USB port and CD drive are defective is 0.02, while the probability that only the CD drive is defective is 0.03 . The probability that the USB port is defective when the CD drive has been found to be defective is?