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Finding the Fourth Proportional to 428.90, 641.98 and 265.78

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Solution

The fourth proportional to 428.90, 641.98 and 265.78 is: 397.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.90 : 641.98 = 265.78 : x
  2. Step 2: Convert to fraction form
    428.90/641.98 = 265.78/x
  3. Step 3: Cross multiply
    428.90x = 641.98 × 265.78
  4. Step 4: Simplify right side
    428.90x = 170,625.08
  5. Step 5: Solve for x
    x = 170,625.08/428.90
  6. Step 6: Final answer
    x = 397.82

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.