Short Answer 
The explanation of the ratio of 1 to 3 involves three steps: understanding the elements of the ratio, calculating the total number of parts (1 + 3 = 4), and determining the proportion each part represents of the whole (the shorter length is 1/4 of the total).
Step 1: Understand the Ratio
Begin by identifying the elements of the ratio. In this case, the ratio is 1 to 3. This means you have two lengths: one shorter length represented by 1 and a longer length represented by 3. It’s helpful to think of these lengths as ratio units and recognize how they relate to the total.
Step 2: Calculate Total Parts
Next, calculate the total number of parts represented in the ratio. You do this by adding both numbers in the ratio together: 1 + 3 = 4. This total implies that the whole length of the line consists of 4 ratio units in total.
Step 3: Determine the Proportion
Finally, find out what fraction each part represents of the whole. For instance, the shorter length, which is 1 ratio unit, is calculated as follows: 1/4 of the entire length (which is 4 ratio units). This shows that the shorter length is one part of the whole that you’ve calculated.