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Finding the Fourth Proportional to 645.45, 890.85 and 396.89

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Solution

The fourth proportional to 645.45, 890.85 and 396.89 is: 547.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.45 : 890.85 = 396.89 : x
  2. Step 2: Convert to fraction form
    645.45/890.85 = 396.89/x
  3. Step 3: Cross multiply
    645.45x = 890.85 × 396.89
  4. Step 4: Simplify right side
    645.45x = 353,565.00
  5. Step 5: Solve for x
    x = 353,565.00/645.45
  6. Step 6: Final answer
    x = 547.78

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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.