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Finding the Fourth Proportional to 285.84, 428.78 and 139.73

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Solution

The fourth proportional to 285.84, 428.78 and 139.73 is: 209.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    285.84 : 428.78 = 139.73 : x
  2. Step 2: Convert to fraction form
    285.84/428.78 = 139.73/x
  3. Step 3: Cross multiply
    285.84x = 428.78 × 139.73
  4. Step 4: Simplify right side
    285.84x = 59,910.59
  5. Step 5: Solve for x
    x = 59,910.59/285.84
  6. Step 6: Final answer
    x = 209.59

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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.