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Finding the Fourth Proportional to 428.56, 642.84 and 280.47

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Solution

The fourth proportional to 428.56, 642.84 and 280.47 is: 420.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.56 : 642.84 = 280.47 : x
  2. Step 2: Convert to fraction form
    428.56/642.84 = 280.47/x
  3. Step 3: Cross multiply
    428.56x = 642.84 × 280.47
  4. Step 4: Simplify right side
    428.56x = 180,297.33
  5. Step 5: Solve for x
    x = 180,297.33/428.56
  6. Step 6: Final answer
    x = 420.71

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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.