Why is partitioning a directed line segment into a ratio of [tex]$1:3$[/tex] not the same as finding [tex]$\frac{1}{3}$[/tex] the length of the directed line segment?

A. The ratio given is part to whole, but fractions compare part to part.
B. The ratio given is part to part. The total number of parts in the whole is [tex]$3-1=2$[/tex].
C. The ratio given is part to part. The total number of parts in the whole is [tex]$1+3=4$[/tex].
D. The ratio given is part to whole, but the associated fraction is [tex]$\frac{3}{1}$[/tex].



Answer :

To address the question of why partitioning a directed line segment into a ratio of [tex]\( 1:3 \)[/tex] is not the same as finding [tex]\( \frac{1}{3} \)[/tex] the length of the directed line segment, let's closely examine the concept of ratios and how they apply to partitioning a segment.

### Understanding Ratios

1. Ratios Explained:
- Part-to-Part Ratio: The ratio [tex]\( 1:3 \)[/tex] means that for every one part, there are three parts of something else. If this represents a directed line segment, it means the line is divided into two segments where one segment is one part and the other segment is three parts.
- Part-to-Whole Ratio: Conversely, if the line segment was described in terms of fractions of the whole, [tex]\( \frac{1}{3} \)[/tex] would mean the line segment is divided such that one segment is [tex]\( \frac{1}{3} \)[/tex] of the total length.

### Partition of the Line Segment

2. Total Number of Parts:
- When given a ratio [tex]\( 1:3 \)[/tex], this refers to part-to-part comparison. To find the total number of parts, we add the parts together: [tex]\( 1 + 3 = 4 \)[/tex].
- Therefore, the directed line segment is divided into four parts where one part is [tex]\( \frac{1}{4} \)[/tex] of the total length, and the remaining three parts together constitute [tex]\( \frac{3}{4} \)[/tex] of the total length.

### Comparing Ratios and Fractions

3. Difference Between [tex]\( \frac{1}{3} \)[/tex] and [tex]\( 1:3 \)[/tex]:
- [tex]\( \frac{1}{3} \)[/tex] indicates a segment that is one-third of the total length of the line.
- [tex]\( 1:3 \)[/tex] indicates that the line segment is divided into four parts, with one part being [tex]\( \frac{1}{4} \)[/tex] of the total length.

### Conclusion

The given partition ratio of [tex]\( 1:3 \)[/tex] means the segment is divided into four parts, with one part measuring [tex]\( \frac{1}{4} \)[/tex] of the total length. This is fundamentally different from simply taking [tex]\( \frac{1}{3} \)[/tex] of the length of the segment.

Thus, the total number of parts in the whole is summed as [tex]\( 1 + 3 = 4 \)[/tex]. This answer correctly explains why the partition [tex]\( 1:3 \)[/tex] is not the same as [tex]\( \frac{1}{3} \)[/tex] the length of the segment. The key understanding is that the ratio [tex]\( 1:3 \)[/tex] represents a total of four parts, not a simple one-third fraction.