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Finding the Fourth Proportional to 687.56, 1,031.80 and 379.64

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Solution

The fourth proportional to 687.56, 1,031.80 and 379.64 is: 569.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.56 : 1,031.80 = 379.64 : x
  2. Step 2: Convert to fraction form
    687.56/1,031.80 = 379.64/x
  3. Step 3: Cross multiply
    687.56x = 1,031.80 × 379.64
  4. Step 4: Simplify right side
    687.56x = 391,712.55
  5. Step 5: Solve for x
    x = 391,712.55/687.56
  6. Step 6: Final answer
    x = 569.71

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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.