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Finding the Fourth Proportional to 128.56, 191.90 and 111.56

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Solution

The fourth proportional to 128.56, 191.90 and 111.56 is: 166.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.56 : 191.90 = 111.56 : x
  2. Step 2: Convert to fraction form
    128.56/191.90 = 111.56/x
  3. Step 3: Cross multiply
    128.56x = 191.90 × 111.56
  4. Step 4: Simplify right side
    128.56x = 21,408.36
  5. Step 5: Solve for x
    x = 21,408.36/128.56
  6. Step 6: Final answer
    x = 166.52

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.