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Finding the Fourth Proportional to 428.10, 640.54 and 254.86

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Solution

The fourth proportional to 428.10, 640.54 and 254.86 is: 381.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.10 : 640.54 = 254.86 : x
  2. Step 2: Convert to fraction form
    428.10/640.54 = 254.86/x
  3. Step 3: Cross multiply
    428.10x = 640.54 × 254.86
  4. Step 4: Simplify right side
    428.10x = 163,248.02
  5. Step 5: Solve for x
    x = 163,248.02/428.10
  6. Step 6: Final answer
    x = 381.33

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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.