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Finding the Fourth Proportional to 136.78, 188.79 and 81.56

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Solution

The fourth proportional to 136.78, 188.79 and 81.56 is: 112.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    136.78 : 188.79 = 81.56 : x
  2. Step 2: Convert to fraction form
    136.78/188.79 = 81.56/x
  3. Step 3: Cross multiply
    136.78x = 188.79 × 81.56
  4. Step 4: Simplify right side
    136.78x = 15,397.71
  5. Step 5: Solve for x
    x = 15,397.71/136.78
  6. Step 6: Final answer
    x = 112.57

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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.