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Finding the Fourth Proportional to 666.20, 999 and 431.56

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Solution

The fourth proportional to 666.20, 999 and 431.56 is: 647.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    666.20 : 999 = 431.56 : x
  2. Step 2: Convert to fraction form
    666.20/999 = 431.56/x
  3. Step 3: Cross multiply
    666.20x = 999 × 431.56
  4. Step 4: Simplify right side
    666.20x = 431,129.69
  5. Step 5: Solve for x
    x = 431,129.69/666.20
  6. Step 6: Final answer
    x = 647.15

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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.