At an international conference, “Red” world countries and “Blue” world countries are the only participants. The ratio of “Red” world participants to “Blue” world participants is 7:3. If one-third of “Red” world participants are left-handed and two-thirds of “Blue” world participants are left-handed, then what is the fraction of the participants who are left-handed?  Select the correct option.
A) 45/21  B) 46/2  C) 13/30  D) 23/6  E) 4/6
Red: Blue = 7:3   Let Red = 7x and Blue = 3x   1/3 of Red are left handed =&gt; 1/3 * 7x = 7x/3 Red left handed   2/3 of Blue are left handed =&gt; 2/3 *3x = 6x/3 blue left handed   fraction of participants who are left handed = total left handed/ total participants = (red left handed + blue left handed)/total participants = (7x/3 + 6x/3)/(7x+3x) = 13/30   Answer : 13/30
<result>C</result>
At an international conference, “Red” world countries and “Blue” world countries are the only participants. The ratio of “Red” world participants to “Blue” world participants is 7:3. If one-third of “Red” world participants are left-handed and two-thirds of “Blue” world participants are left-handed, then what is the fraction of the participants who are left-handed?