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Finding the Fourth Proportional to 819.78, 1,228.93 and 409.05

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Solution

The fourth proportional to 819.78, 1,228.93 and 409.05 is: 613.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.78 : 1,228.93 = 409.05 : x
  2. Step 2: Convert to fraction form
    819.78/1,228.93 = 409.05/x
  3. Step 3: Cross multiply
    819.78x = 1,228.93 × 409.05
  4. Step 4: Simplify right side
    819.78x = 502,687.67
  5. Step 5: Solve for x
    x = 502,687.67/819.78
  6. Step 6: Final answer
    x = 613.20

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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.