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Finding the Fourth Proportional to 428.86, 643.20 and 140.29

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Solution

The fourth proportional to 428.86, 643.20 and 140.29 is: 210.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.86 : 643.20 = 140.29 : x
  2. Step 2: Convert to fraction form
    428.86/643.20 = 140.29/x
  3. Step 3: Cross multiply
    428.86x = 643.20 × 140.29
  4. Step 4: Simplify right side
    428.86x = 90,234.53
  5. Step 5: Solve for x
    x = 90,234.53/428.86
  6. Step 6: Final answer
    x = 210.41

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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.