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Finding the Fourth Proportional to 428.30, 642.62 and 255.12

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Solution

The fourth proportional to 428.30, 642.62 and 255.12 is: 382.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.30 : 642.62 = 255.12 : x
  2. Step 2: Convert to fraction form
    428.30/642.62 = 255.12/x
  3. Step 3: Cross multiply
    428.30x = 642.62 × 255.12
  4. Step 4: Simplify right side
    428.30x = 163,945.21
  5. Step 5: Solve for x
    x = 163,945.21/428.30
  6. Step 6: Final answer
    x = 382.78

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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.