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Finding the Fourth Proportional to 711.72, 987.39 and 685.80

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Solution

The fourth proportional to 711.72, 987.39 and 685.80 is: 951.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    711.72 : 987.39 = 685.80 : x
  2. Step 2: Convert to fraction form
    711.72/987.39 = 685.80/x
  3. Step 3: Cross multiply
    711.72x = 987.39 × 685.80
  4. Step 4: Simplify right side
    711.72x = 677,152.06
  5. Step 5: Solve for x
    x = 677,152.06/711.72
  6. Step 6: Final answer
    x = 951.43

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Double scale
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.