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Finding the Fourth Proportional to 428.61, 643.11 and 320.61

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Solution

The fourth proportional to 428.61, 643.11 and 320.61 is: 481.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.61 : 643.11 = 320.61 : x
  2. Step 2: Convert to fraction form
    428.61/643.11 = 320.61/x
  3. Step 3: Cross multiply
    428.61x = 643.11 × 320.61
  4. Step 4: Simplify right side
    428.61x = 206,187.50
  5. Step 5: Solve for x
    x = 206,187.50/428.61
  6. Step 6: Final answer
    x = 481.06

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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.