Question

    A car travels 150 miles at a constant speed of 50 miles

    per hour. It then makes a 30-minute stop before continuing its journey at a constant speed of 60 miles per hour for another 100 miles. What is the approximate average speed for the entire journey?
    A 48 miles per hour Correct Answer Incorrect Answer
    B 65 miles per hour Correct Answer Incorrect Answer
    C 20 miles per hour Correct Answer Incorrect Answer
    D 69 miles per hour Correct Answer Incorrect Answer

    Solution

    Total distance = 150 + 100 = 250 miles Time taken for the first 150 miles = 150/50 = 3 hours Time taken for the last 100 miles = 100/60 = 5/3 hours Total time = 3 + 0.5 (for the stop) + 5/3 = 31/6 hours Average speed = 250 / (31/6) = 1500/31 ≈ 48.38 miles per hour Answer: (A)

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