Difference between revisions of "2016 AMC 8 Problems/Problem 14"
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Since he uses a gallon of gas every <math>35</math> miles, he had used <math>\frac{350}{35} = 10</math> gallons after <math>350</math> miles. Therefore, after the first leg of his trip he had <math>14 - 10 = 4</math> gallons of gas left. Then, he bought <math>8</math> gallons of gas, which brought him up to <math>12</math> gallons of gas in his gas tank. When he arrived, he had <math>\frac{1}{2} \cdot 14 = 7</math> gallons of gas. So he used <math>5</math> gallons of gas on the second leg of his trip. Therefore, the second part of his trip covered <math>5 \cdot 35 = 175</math> miles. Adding this to the <math>350</math> miles, we see that he drove <math>350 + 175 = \textbf{(A)} 525</math> miles. | Since he uses a gallon of gas every <math>35</math> miles, he had used <math>\frac{350}{35} = 10</math> gallons after <math>350</math> miles. Therefore, after the first leg of his trip he had <math>14 - 10 = 4</math> gallons of gas left. Then, he bought <math>8</math> gallons of gas, which brought him up to <math>12</math> gallons of gas in his gas tank. When he arrived, he had <math>\frac{1}{2} \cdot 14 = 7</math> gallons of gas. So he used <math>5</math> gallons of gas on the second leg of his trip. Therefore, the second part of his trip covered <math>5 \cdot 35 = 175</math> miles. Adding this to the <math>350</math> miles, we see that he drove <math>350 + 175 = \textbf{(A)} 525</math> miles. | ||
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Revision as of 10:59, 23 November 2016
Karl's car uses a gallon of gas every miles, and his gas tank holds gallons when it is full. One day, Karl started with a full tank of gas, drove miles, bought gallons of gas, and continued driving to his destination. When he arrived, his gas tank was half full. How many miles did Karl drive that day?
Solution
Since he uses a gallon of gas every miles, he had used gallons after miles. Therefore, after the first leg of his trip he had gallons of gas left. Then, he bought gallons of gas, which brought him up to gallons of gas in his gas tank. When he arrived, he had gallons of gas. So he used gallons of gas on the second leg of his trip. Therefore, the second part of his trip covered miles. Adding this to the miles, we see that he drove miles.