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Finding the Fourth Proportional to 687.39, 1,031.61 and 480.61

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Solution

The fourth proportional to 687.39, 1,031.61 and 480.61 is: 721.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.39 : 1,031.61 = 480.61 : x
  2. Step 2: Convert to fraction form
    687.39/1,031.61 = 480.61/x
  3. Step 3: Cross multiply
    687.39x = 1,031.61 × 480.61
  4. Step 4: Simplify right side
    687.39x = 495,802.08
  5. Step 5: Solve for x
    x = 495,802.08/687.39
  6. Step 6: Final answer
    x = 721.28

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.