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Finding the Fourth Proportional to 129.78, 178.74 and 111.36

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Solution

The fourth proportional to 129.78, 178.74 and 111.36 is: 153.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.78 : 178.74 = 111.36 : x
  2. Step 2: Convert to fraction form
    129.78/178.74 = 111.36/x
  3. Step 3: Cross multiply
    129.78x = 178.74 × 111.36
  4. Step 4: Simplify right side
    129.78x = 19,904.49
  5. Step 5: Solve for x
    x = 19,904.49/129.78
  6. Step 6: Final answer
    x = 153.37

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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.