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Finding the Fourth Proportional to 688.78, 1,031.40 and 380.29

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Solution

The fourth proportional to 688.78, 1,031.40 and 380.29 is: 569.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    688.78 : 1,031.40 = 380.29 : x
  2. Step 2: Convert to fraction form
    688.78/1,031.40 = 380.29/x
  3. Step 3: Cross multiply
    688.78x = 1,031.40 × 380.29
  4. Step 4: Simplify right side
    688.78x = 392,228.53
  5. Step 5: Solve for x
    x = 392,228.53/688.78
  6. Step 6: Final answer
    x = 569.46

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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.