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Finding the Fourth Proportional to 819.48, 1,228.78 and 428.52

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Solution

The fourth proportional to 819.48, 1,228.78 and 428.52 is: 642.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.48 : 1,228.78 = 428.52 : x
  2. Step 2: Convert to fraction form
    819.48/1,228.78 = 428.52/x
  3. Step 3: Cross multiply
    819.48x = 1,228.78 × 428.52
  4. Step 4: Simplify right side
    819.48x = 526,556.81
  5. Step 5: Solve for x
    x = 526,556.81/819.48
  6. Step 6: Final answer
    x = 642.55

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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.