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Finding the Fourth Proportional to 680.20, 1,020.30 and 388.60

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Solution

The fourth proportional to 680.20, 1,020.30 and 388.60 is: 582.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.20 : 1,020.30 = 388.60 : x
  2. Step 2: Convert to fraction form
    680.20/1,020.30 = 388.60/x
  3. Step 3: Cross multiply
    680.20x = 1,020.30 × 388.60
  4. Step 4: Simplify right side
    680.20x = 396,488.58
  5. Step 5: Solve for x
    x = 396,488.58/680.20
  6. Step 6: Final answer
    x = 582.90

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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.