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Finding the Fourth Proportional to 428.90, 638.69 and 427.68

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Solution

The fourth proportional to 428.90, 638.69 and 427.68 is: 636.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.90 : 638.69 = 427.68 : x
  2. Step 2: Convert to fraction form
    428.90/638.69 = 427.68/x
  3. Step 3: Cross multiply
    428.90x = 638.69 × 427.68
  4. Step 4: Simplify right side
    428.90x = 273,152.80
  5. Step 5: Solve for x
    x = 273,152.80/428.90
  6. Step 6: Final answer
    x = 636.88

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.