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Finding the Fourth Proportional to 421.28, 579.96 and 355.76

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Solution

The fourth proportional to 421.28, 579.96 and 355.76 is: 489.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.28 : 579.96 = 355.76 : x
  2. Step 2: Convert to fraction form
    421.28/579.96 = 355.76/x
  3. Step 3: Cross multiply
    421.28x = 579.96 × 355.76
  4. Step 4: Simplify right side
    421.28x = 206,326.57
  5. Step 5: Solve for x
    x = 206,326.57/421.28
  6. Step 6: Final answer
    x = 489.76

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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.