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Finding the Fourth Proportional to 420.81, 580.14 and 355.20

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Solution

The fourth proportional to 420.81, 580.14 and 355.20 is: 489.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.81 : 580.14 = 355.20 : x
  2. Step 2: Convert to fraction form
    420.81/580.14 = 355.20/x
  3. Step 3: Cross multiply
    420.81x = 580.14 × 355.20
  4. Step 4: Simplify right side
    420.81x = 206,065.73
  5. Step 5: Solve for x
    x = 206,065.73/420.81
  6. Step 6: Final answer
    x = 489.69

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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.