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Finding the Fourth Proportional to 999.72, 1,379.82 and 645.39

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Solution

The fourth proportional to 999.72, 1,379.82 and 645.39 is: 890.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    999.72 : 1,379.82 = 645.39 : x
  2. Step 2: Convert to fraction form
    999.72/1,379.82 = 645.39/x
  3. Step 3: Cross multiply
    999.72x = 1,379.82 × 645.39
  4. Step 4: Simplify right side
    999.72x = 890,522.03
  5. Step 5: Solve for x
    x = 890,522.03/999.72
  6. Step 6: Final answer
    x = 890.77

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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.