It is the same as 6:5. 6+5=11, so it means the same as 6/11 to 5/11, so if you had 11 objects of two different types, you would have 6 of one and 5 of the other. Or if you had 220 students, boys and girls, and the ratio was boys:girls=6:5 or 60:50 there would be 6/11 of 220=120 boys and 5/11 of 220=100 girls.