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Finding the Fourth Proportional to 613.20, 920.70 and 431.40

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Solution

The fourth proportional to 613.20, 920.70 and 431.40 is: 647.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    613.20 : 920.70 = 431.40 : x
  2. Step 2: Convert to fraction form
    613.20/920.70 = 431.40/x
  3. Step 3: Cross multiply
    613.20x = 920.70 × 431.40
  4. Step 4: Simplify right side
    613.20x = 397,189.98
  5. Step 5: Solve for x
    x = 397,189.98/613.20
  6. Step 6: Final answer
    x = 647.73

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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.