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Finding the Fourth Proportional to 819.79, 1,229.86 and 380.72

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Solution

The fourth proportional to 819.79, 1,229.86 and 380.72 is: 571.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.79 : 1,229.86 = 380.72 : x
  2. Step 2: Convert to fraction form
    819.79/1,229.86 = 380.72/x
  3. Step 3: Cross multiply
    819.79x = 1,229.86 × 380.72
  4. Step 4: Simplify right side
    819.79x = 468,227.86
  5. Step 5: Solve for x
    x = 468,227.86/819.79
  6. Step 6: Final answer
    x = 571.16

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.