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Finding the Fourth Proportional to 999.80, 1,379.70 and 557.72

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Solution

The fourth proportional to 999.80, 1,379.70 and 557.72 is: 769.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    999.80 : 1,379.70 = 557.72 : x
  2. Step 2: Convert to fraction form
    999.80/1,379.70 = 557.72/x
  3. Step 3: Cross multiply
    999.80x = 1,379.70 × 557.72
  4. Step 4: Simplify right side
    999.80x = 769,486.28
  5. Step 5: Solve for x
    x = 769,486.28/999.80
  6. Step 6: Final answer
    x = 769.64

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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.