Question

Difficulty: MediumFraction Operations

A carpenter is sorting four wooden planks based on their lengths to construct a custom frame. The lengths of the planks, in feet, are listed below. Sequence the plank lengths from shortest to longest.

  1. 11131\frac{1}{3} feet
  2. 21381\frac{3}{8} feet
  3. 375\frac{7}{5} feet
  4. 41712\frac{17}{12} feet

Answer

The correct ascending sequence is 1131\frac{1}{3} feet, 1381\frac{3}{8} feet, 75\frac{7}{5} feet, and 1712\frac{17}{12} feet.
To compare fractions with different denominators, they must be converted to a common denominator. The least common multiple of 33, 88, 55, and 1212 is 120120. Converting all values yields 160120\frac{160}{120}, 165120\frac{165}{120}, 168120\frac{168}{120}, and 170120\frac{170}{120}. Arranging these from smallest to largest gives the proper sequence of 1131\frac{1}{3} feet, 1381\frac{3}{8} feet, 75\frac{7}{5} feet, and 1712\frac{17}{12} feet.

Step-by-Step Solution

1
Convert all mixed numbers to improper fractions.
138=1181\frac{3}{8} = \frac{11}{8} and 113=431\frac{1}{3} = \frac{4}{3}.
Fractions must be in a consistent improper format to find a common denominator efficiently.
2
Find the least common multiple (LCM) for the denominators 88, 1212, 33, and 55.
The LCM of 88, 1212, 33, and 55 is 120120.
A common denominator is required to directly compare the relative sizes of the fractions.
3
Convert each fraction to an equivalent fraction with a denominator of 120120.
43=160120\frac{4}{3} = \frac{160}{120}, 118=165120\frac{11}{8} = \frac{165}{120}, 75=168120\frac{7}{5} = \frac{168}{120}, and 1712=170120\frac{17}{12} = \frac{170}{120}.
Normalizing the denominators isolates the variation to the numerators, making comparison straightforward.
4
Arrange the fractions by comparing their normalized numerators from smallest to largest.
160<165<168<170160 < 165 < 168 < 170, which corresponds to the original values 113<138<75<17121\frac{1}{3} < 1\frac{3}{8} < \frac{7}{5} < \frac{17}{12}.
The problem specifies sequencing the plank lengths from shortest to longest.

Key Concept

Ordering and Comparing Fractions

Alternative Method

Convert each fraction to its decimal equivalent: 113≈1.3331\frac{1}{3} \approx 1.333, 138=1.3751\frac{3}{8} = 1.375, 75=1.400\frac{7}{5} = 1.400, and 1712≈1.417\frac{17}{12} \approx 1.417. The decimals can then be easily ordered from least to greatest.
Estimated Time:1m 0s
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