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Finding the Fourth Proportional to 672.45, 1,007.85 and 428.43

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Solution

The fourth proportional to 672.45, 1,007.85 and 428.43 is: 642.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    672.45 : 1,007.85 = 428.43 : x
  2. Step 2: Convert to fraction form
    672.45/1,007.85 = 428.43/x
  3. Step 3: Cross multiply
    672.45x = 1,007.85 × 428.43
  4. Step 4: Simplify right side
    672.45x = 431,793.18
  5. Step 5: Solve for x
    x = 431,793.18/672.45
  6. Step 6: Final answer
    x = 642.12

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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.