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Finding the Fourth Proportional to 789.21, 1,089.10 and 439.90

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Solution

The fourth proportional to 789.21, 1,089.10 and 439.90 is: 607.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    789.21 : 1,089.10 = 439.90 : x
  2. Step 2: Convert to fraction form
    789.21/1,089.10 = 439.90/x
  3. Step 3: Cross multiply
    789.21x = 1,089.10 × 439.90
  4. Step 4: Simplify right side
    789.21x = 479,095.09
  5. Step 5: Solve for x
    x = 479,095.09/789.21
  6. Step 6: Final answer
    x = 607.06

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.