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Finding the Fourth Proportional to 999.90, 1,379.80 and 557.79

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Solution

The fourth proportional to 999.90, 1,379.80 and 557.79 is: 769.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    999.90 : 1,379.80 = 557.79 : x
  2. Step 2: Convert to fraction form
    999.90/1,379.80 = 557.79/x
  3. Step 3: Cross multiply
    999.90x = 1,379.80 × 557.79
  4. Step 4: Simplify right side
    999.90x = 769,641.93
  5. Step 5: Solve for x
    x = 769,641.93/999.90
  6. Step 6: Final answer
    x = 769.72

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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.