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Finding the Fourth Proportional to 658.21, 987.21 and 428.73

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Solution

The fourth proportional to 658.21, 987.21 and 428.73 is: 643.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    658.21 : 987.21 = 428.73 : x
  2. Step 2: Convert to fraction form
    658.21/987.21 = 428.73/x
  3. Step 3: Cross multiply
    658.21x = 987.21 × 428.73
  4. Step 4: Simplify right side
    658.21x = 423,246.54
  5. Step 5: Solve for x
    x = 423,246.54/658.21
  6. Step 6: Final answer
    x = 643.03

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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.