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Finding the Fourth Proportional to 819.72, 1,128.60 and 778.68

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Solution

The fourth proportional to 819.72, 1,128.60 and 778.68 is: 1,072.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.72 : 1,128.60 = 778.68 : x
  2. Step 2: Convert to fraction form
    819.72/1,128.60 = 778.68/x
  3. Step 3: Cross multiply
    819.72x = 1,128.60 × 778.68
  4. Step 4: Simplify right side
    819.72x = 878,818.25
  5. Step 5: Solve for x
    x = 878,818.25/819.72
  6. Step 6: Final answer
    x = 1,072.10

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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.