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Finding the Fourth Proportional to 789.21, 1,089.56 and 709.43

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Solution

The fourth proportional to 789.21, 1,089.56 and 709.43 is: 979.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    789.21 : 1,089.56 = 709.43 : x
  2. Step 2: Convert to fraction form
    789.21/1,089.56 = 709.43/x
  3. Step 3: Cross multiply
    789.21x = 1,089.56 × 709.43
  4. Step 4: Simplify right side
    789.21x = 772,957.56
  5. Step 5: Solve for x
    x = 772,957.56/789.21
  6. Step 6: Final answer
    x = 979.41

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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.