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Finding the Fourth Proportional to 428.90, 643.37 and 140.36

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Solution

The fourth proportional to 428.90, 643.37 and 140.36 is: 210.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.90 : 643.37 = 140.36 : x
  2. Step 2: Convert to fraction form
    428.90/643.37 = 140.36/x
  3. Step 3: Cross multiply
    428.90x = 643.37 × 140.36
  4. Step 4: Simplify right side
    428.90x = 90,299.49
  5. Step 5: Solve for x
    x = 90,299.49/428.90
  6. Step 6: Final answer
    x = 210.54

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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.