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Finding the Fourth Proportional to 999.20, 1,378.88 and 557.10

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Solution

The fourth proportional to 999.20, 1,378.88 and 557.10 is: 768.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    999.20 : 1,378.88 = 557.10 : x
  2. Step 2: Convert to fraction form
    999.20/1,378.88 = 557.10/x
  3. Step 3: Cross multiply
    999.20x = 1,378.88 × 557.10
  4. Step 4: Simplify right side
    999.20x = 768,164.37
  5. Step 5: Solve for x
    x = 768,164.37/999.20
  6. Step 6: Final answer
    x = 768.78

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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.