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Finding the Fourth Proportional to 285.96, 428.85 and 139.68

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Solution

The fourth proportional to 285.96, 428.85 and 139.68 is: 209.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    285.96 : 428.85 = 139.68 : x
  2. Step 2: Convert to fraction form
    285.96/428.85 = 139.68/x
  3. Step 3: Cross multiply
    285.96x = 428.85 × 139.68
  4. Step 4: Simplify right side
    285.96x = 59,901.77
  5. Step 5: Solve for x
    x = 59,901.77/285.96
  6. Step 6: Final answer
    x = 209.48

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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.