A car repair shop offers its customers free coffee while they wait. By the end of the day, the coffee urn, which had started out with 8 1/2 gallons of coffee, was left with 2 1/3 g... A car repair shop offers its customers free coffee while they wait. By the end of the day, the coffee urn, which had started out with 8 1/2 gallons of coffee, was left with 2 1/3 gallons. How many gallons of coffee had been dispensed? Write your answer as a fraction or as a whole or mixed number.
Understand the Problem
The question is asking us to determine how many gallons of coffee have been dispensed from a coffee urn that started with 8 1/2 gallons and is left with 2 1/3 gallons. To solve it, we will subtract the amount left from the initial amount.
Answer
The amount of coffee dispensed is $6 \frac{1}{6}$ gallons.
Answer for screen readers
The amount of coffee dispensed is $6 \frac{1}{6}$ gallons.
Steps to Solve
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Convert mixed numbers to improper fractions
Convert $8 \frac{1}{2}$ and $2 \frac{1}{3}$ to improper fractions:
$8 \frac{1}{2} = \frac{17}{2}$ (calculated as $8 \times 2 + 1 = 17$)
$2 \frac{1}{3} = \frac{7}{3}$ (calculated as $2 \times 3 + 1 = 7$)
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Find a common denominator
The least common denominator (LCD) of the fractions $\frac{17}{2}$ and $\frac{7}{3}$ is $6$.
Convert the fractions:
$$ \frac{17}{2} = \frac{17 \times 3}{2 \times 3} = \frac{51}{6} $$
$$ \frac{7}{3} = \frac{7 \times 2}{3 \times 2} = \frac{14}{6} $$
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Subtract the fractions
Now subtract the two fractions:
$$ \frac{51}{6} - \frac{14}{6} = \frac{51 - 14}{6} = \frac{37}{6} $$
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Convert the result back to a mixed number
To convert $\frac{37}{6}$ to a mixed number, divide $37$ by $6$:
$$ 37 \div 6 = 6 \text{ remainder } 1 $$
So,
$$ \frac{37}{6} = 6 \frac{1}{6} $$
The amount of coffee dispensed is $6 \frac{1}{6}$ gallons.
More Information
The problem demonstrates how to convert mixed numbers to improper fractions, perform subtraction, and convert back to a mixed number.
Tips
- Forgetting to find a common denominator before subtracting fractions.
- Not converting mixed numbers to improper fractions correctly.
- Miscalculating during the conversion back to a mixed number.
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