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Finding the Fourth Proportional to 128.94, 178.05 and 111.49

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Solution

The fourth proportional to 128.94, 178.05 and 111.49 is: 153.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.94 : 178.05 = 111.49 : x
  2. Step 2: Convert to fraction form
    128.94/178.05 = 111.49/x
  3. Step 3: Cross multiply
    128.94x = 178.05 × 111.49
  4. Step 4: Simplify right side
    128.94x = 19,850.79
  5. Step 5: Solve for x
    x = 19,850.79/128.94
  6. Step 6: Final answer
    x = 153.95

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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.