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Finding the Fourth Proportional to 661.20, 990 and 487.44

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Solution

The fourth proportional to 661.20, 990 and 487.44 is: 729.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.20 : 990 = 487.44 : x
  2. Step 2: Convert to fraction form
    661.20/990 = 487.44/x
  3. Step 3: Cross multiply
    661.20x = 990 × 487.44
  4. Step 4: Simplify right side
    661.20x = 482,565.60
  5. Step 5: Solve for x
    x = 482,565.60/661.20
  6. Step 6: Final answer
    x = 729.83

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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.