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Finding the Fourth Proportional to 136.86, 188.72 and 87.68

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Solution

The fourth proportional to 136.86, 188.72 and 87.68 is: 120.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    136.86 : 188.72 = 87.68 : x
  2. Step 2: Convert to fraction form
    136.86/188.72 = 87.68/x
  3. Step 3: Cross multiply
    136.86x = 188.72 × 87.68
  4. Step 4: Simplify right side
    136.86x = 16,546.97
  5. Step 5: Solve for x
    x = 16,546.97/136.86
  6. Step 6: Final answer
    x = 120.90

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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.