Question

related questions: lesson 6: common algebra word problems

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q. at 8:30 a.m., the garcias started driving north at a speed of 48 miles per hour. twenty minutes later, the parkers began driving north from the same point. if the parkers drive 60 miles per hour, at what time will they catch up with the garcias?

10:00
10:10
10:20
10:30

Explanation:

Calculate the lead distance

Using the Unit Conversion and Relative Speed Word Problems knowledge points

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Determine the relative speed

Using the Relative Speed Word Problems knowledge point

$$ v_{\text{relative}} = v_{\text{Parkers}} - v_{\text{Garcias}} = 60\text{ mph} - 48\text{ mph} = 12\text{ mph} $$

Calculate the catch-up time

Using the Relative Speed Word Problems knowledge point

$$ t_{\text{catch-up}} = \frac{d_{\text{lead}}}{v_{\text{relative}}} = \frac{16\text{ miles}}{12\text{ mph}} = \frac{4}{3}\text{ hours} = 1\text{ hour } 20\text{ minutes} $$

Determine the final clock time

Using the Time Math knowledge point

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Answer:

• 10:00
• 10:10 (Correct answer)
• 10:20
• 10:30