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Finding the Fourth Proportional to 645.38, 890.42 and 396.48

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Solution

The fourth proportional to 645.38, 890.42 and 396.48 is: 547.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.38 : 890.42 = 396.48 : x
  2. Step 2: Convert to fraction form
    645.38/890.42 = 396.48/x
  3. Step 3: Cross multiply
    645.38x = 890.42 × 396.48
  4. Step 4: Simplify right side
    645.38x = 353,033.72
  5. Step 5: Solve for x
    x = 353,033.72/645.38
  6. Step 6: Final answer
    x = 547.02

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Double scale
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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.