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Finding the Fourth Proportional to 428.73, 642.80 and 219.99

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Solution

The fourth proportional to 428.73, 642.80 and 219.99 is: 329.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.73 : 642.80 = 219.99 : x
  2. Step 2: Convert to fraction form
    428.73/642.80 = 219.99/x
  3. Step 3: Cross multiply
    428.73x = 642.80 × 219.99
  4. Step 4: Simplify right side
    428.73x = 141,405.26
  5. Step 5: Solve for x
    x = 141,405.26/428.73
  6. Step 6: Final answer
    x = 329.82

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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.