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Finding the Fourth Proportional to 819.20, 1,129.20 and 644.32

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Solution

The fourth proportional to 819.20, 1,129.20 and 644.32 is: 888.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.20 : 1,129.20 = 644.32 : x
  2. Step 2: Convert to fraction form
    819.20/1,129.20 = 644.32/x
  3. Step 3: Cross multiply
    819.20x = 1,129.20 × 644.32
  4. Step 4: Simplify right side
    819.20x = 727,566.14
  5. Step 5: Solve for x
    x = 727,566.14/819.20
  6. Step 6: Final answer
    x = 888.14

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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.