Write the following proportions.
39 children is to 45 bicycles as 13 children is to 15 bicycles
To write the given information as proportions, we will express the relationship between children and bicycles in fractional form, and then set the two fractions equal to each other, since they represent equivalent ratios.
The proportion for the first set of data (39 children to 45 bicycles) is:
39 children / 45 bicycles
The proportion for the second set of data (13 children to 15 bicycles) is:
13 children / 15 bicycles
Setting these two proportions equal to each other, we get:
39 children / 45 bicycles = 13 children / 15 bicycles
This proportion indicates that for every 39 children there are 45 bicycles, which is the same ratio as 13 children to 15 bicycles. This is an example of a direct proportion -- as the number of children increases, the number of bicycles also increases at the same rate.