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Finding the Fourth Proportional to 645.42, 890.55 and 396.78

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Solution

The fourth proportional to 645.42, 890.55 and 396.78 is: 547.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.42 : 890.55 = 396.78 : x
  2. Step 2: Convert to fraction form
    645.42/890.55 = 396.78/x
  3. Step 3: Cross multiply
    645.42x = 890.55 × 396.78
  4. Step 4: Simplify right side
    645.42x = 353,352.43
  5. Step 5: Solve for x
    x = 353,352.43/645.42
  6. Step 6: Final answer
    x = 547.48

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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.