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Finding the Fourth Proportional to 428.40, 638.96 and 389.52

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Solution

The fourth proportional to 428.40, 638.96 and 389.52 is: 580.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.40 : 638.96 = 389.52 : x
  2. Step 2: Convert to fraction form
    428.40/638.96 = 389.52/x
  3. Step 3: Cross multiply
    428.40x = 638.96 × 389.52
  4. Step 4: Simplify right side
    428.40x = 248,887.70
  5. Step 5: Solve for x
    x = 248,887.70/428.40
  6. Step 6: Final answer
    x = 580.97

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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.