Question

Difficulty: HardFraction Addition and Subtraction in Context

A technician is preparing a heavy-duty cable that will be cut into three separate sections. The total length of the cable before any cuts is 154515 \frac{4}{5} yards. The first section measures 4134 \frac{1}{3} yards long, and the second section measures exactly 66 feet long. Assuming no material is lost during cutting, how many yards long must the third section be?

  1. 97159 \frac{7}{15}Answer
  2. B
    57155 \frac{7}{15}
  3. C
    9389 \frac{3}{8}
  4. D
    6136 \frac{1}{3}

Answer

The third section must be 97159 \frac{7}{15} yards long.
The correct answer is found by first converting the 6 feet into 2 yards. Adding this to the first section gives a total used length of 6136 \frac{1}{3} yards. By finding a common denominator of 15, the total length (15121515 \frac{12}{15}) minus the used length (65156 \frac{5}{15}) correctly equals 97159 \frac{7}{15} yards.

Step-by-Step Solution

1
Convert the length of the second section from feet to yards so all units match.
6 feet=2 yards6 \text{ feet} = 2 \text{ yards}.
Measurements must be in the same unit (yards) before they can be added or subtracted.
2
Add the lengths of the first and second sections to find the total length used so far.
413+2=613 yards4 \frac{1}{3} + 2 = 6 \frac{1}{3} \text{ yards}.
This establishes the combined length that needs to be subtracted from the whole.
3
Find a common denominator for the total cable length and the used cable length.
The common denominator for 55 and 33 is 1515. Thus, 1545=15121515 \frac{4}{5} = 15 \frac{12}{15} and 613=65156 \frac{1}{3} = 6 \frac{5}{15}.
Fractions must have common denominators before they can be subtracted.
4
Subtract the used length from the total length to find the length of the third section.
151215−6515=9715 yards15 \frac{12}{15} - 6 \frac{5}{15} = 9 \frac{7}{15} \text{ yards}.
Subtracting the sum of the known parts from the total length yields the remaining unknown part.

Key Concept

Adding and subtracting mixed numbers with unlike denominators after converting units.
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