A grade has 81 girls and 72 boys. The grade is spilt into groups that have the same ratio of boys to girls as the whole grade. How many girls are in a group that has 16 boys?
There are 81 girls to every 72 boys in total, which can be represented by 81/72, which put into decimal form, is 1.125. If you then take the number of boys in the group, 16, and multiply it by this number (because the problem states that the ratio is constant) you can find the number of girls in the group. 16*1.125=18 So there are 18 girls in a group with 16 boys.