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Finding the Fourth Proportional to 691.18, 1,037.28 and 431.56

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Solution

The fourth proportional to 691.18, 1,037.28 and 431.56 is: 647.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    691.18 : 1,037.28 = 431.56 : x
  2. Step 2: Convert to fraction form
    691.18/1,037.28 = 431.56/x
  3. Step 3: Cross multiply
    691.18x = 1,037.28 × 431.56
  4. Step 4: Simplify right side
    691.18x = 447,648.56
  5. Step 5: Solve for x
    x = 447,648.56/691.18
  6. Step 6: Final answer
    x = 647.66

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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.