Mathematics for IGCSE & O level - Ratio And Proportion (Section 1 - No. 35)
In a certain class, the ratio of boys to girls is 3:4. If there are a total of 28 students in the class, how many boys are there?
9
12
16
21
Vysvětlení
Boys:Girls=3:4. 3+4=7, 28/7 = 4. so boys 3*4=12