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Finding the Fourth Proportional to 687.68, 1,031.30 and 379.68

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Solution

The fourth proportional to 687.68, 1,031.30 and 379.68 is: 569.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.68 : 1,031.30 = 379.68 : x
  2. Step 2: Convert to fraction form
    687.68/1,031.30 = 379.68/x
  3. Step 3: Cross multiply
    687.68x = 1,031.30 × 379.68
  4. Step 4: Simplify right side
    687.68x = 391,562.09
  5. Step 5: Solve for x
    x = 391,562.09/687.68
  6. Step 6: Final answer
    x = 569.39

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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.