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Finding the Fourth Proportional to 645.70, 891.12 and 383.80

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Solution

The fourth proportional to 645.70, 891.12 and 383.80 is: 529.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.70 : 891.12 = 383.80 : x
  2. Step 2: Convert to fraction form
    645.70/891.12 = 383.80/x
  3. Step 3: Cross multiply
    645.70x = 891.12 × 383.80
  4. Step 4: Simplify right side
    645.70x = 342,011.86
  5. Step 5: Solve for x
    x = 342,011.86/645.70
  6. Step 6: Final answer
    x = 529.68

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.