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Finding the Fourth Proportional to 920.82, 1,379.34 and 687

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Solution

The fourth proportional to 920.82, 1,379.34 and 687 is: 1,029.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    920.82 : 1,379.34 = 687 : x
  2. Step 2: Convert to fraction form
    920.82/1,379.34 = 687/x
  3. Step 3: Cross multiply
    920.82x = 1,379.34 × 687
  4. Step 4: Simplify right side
    920.82x = 947,606.58
  5. Step 5: Solve for x
    x = 947,606.58/920.82
  6. Step 6: Final answer
    x = 1,029.09

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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.