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Finding the Fourth Proportional to 221.15, 331.45 and 139.81

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Solution

The fourth proportional to 221.15, 331.45 and 139.81 is: 209.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.15 : 331.45 = 139.81 : x
  2. Step 2: Convert to fraction form
    221.15/331.45 = 139.81/x
  3. Step 3: Cross multiply
    221.15x = 331.45 × 139.81
  4. Step 4: Simplify right side
    221.15x = 46,340.02
  5. Step 5: Solve for x
    x = 46,340.02/221.15
  6. Step 6: Final answer
    x = 209.54

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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.