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Finding the Fourth Proportional to 221.06, 305.21 and 138.20

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Solution

The fourth proportional to 221.06, 305.21 and 138.20 is: 190.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.06 : 305.21 = 138.20 : x
  2. Step 2: Convert to fraction form
    221.06/305.21 = 138.20/x
  3. Step 3: Cross multiply
    221.06x = 305.21 × 138.20
  4. Step 4: Simplify right side
    221.06x = 42,180.02
  5. Step 5: Solve for x
    x = 42,180.02/221.06
  6. Step 6: Final answer
    x = 190.81

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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.