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Finding the Fourth Proportional to 221.55, 305.73 and 138.72

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Solution

The fourth proportional to 221.55, 305.73 and 138.72 is: 191.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.55 : 305.73 = 138.72 : x
  2. Step 2: Convert to fraction form
    221.55/305.73 = 138.72/x
  3. Step 3: Cross multiply
    221.55x = 305.73 × 138.72
  4. Step 4: Simplify right side
    221.55x = 42,410.87
  5. Step 5: Solve for x
    x = 42,410.87/221.55
  6. Step 6: Final answer
    x = 191.43

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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.