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Finding the Fourth Proportional to 221.57, 305.91 and 138.75

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Solution

The fourth proportional to 221.57, 305.91 and 138.75 is: 191.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.57 : 305.91 = 138.75 : x
  2. Step 2: Convert to fraction form
    221.57/305.91 = 138.75/x
  3. Step 3: Cross multiply
    221.57x = 305.91 × 138.75
  4. Step 4: Simplify right side
    221.57x = 42,443.87
  5. Step 5: Solve for x
    x = 42,443.87/221.57
  6. Step 6: Final answer
    x = 191.56

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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.