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Finding the Fourth Proportional to 645.24, 890.20 and 396.40

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Solution

The fourth proportional to 645.24, 890.20 and 396.40 is: 546.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.24 : 890.20 = 396.40 : x
  2. Step 2: Convert to fraction form
    645.24/890.20 = 396.40/x
  3. Step 3: Cross multiply
    645.24x = 890.20 × 396.40
  4. Step 4: Simplify right side
    645.24x = 352,875.28
  5. Step 5: Solve for x
    x = 352,875.28/645.24
  6. Step 6: Final answer
    x = 546.89

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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.