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Finding the Fourth Proportional to 136.61, 188.43 and 86.78

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Solution

The fourth proportional to 136.61, 188.43 and 86.78 is: 119.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    136.61 : 188.43 = 86.78 : x
  2. Step 2: Convert to fraction form
    136.61/188.43 = 86.78/x
  3. Step 3: Cross multiply
    136.61x = 188.43 × 86.78
  4. Step 4: Simplify right side
    136.61x = 16,351.01
  5. Step 5: Solve for x
    x = 16,351.01/136.61
  6. Step 6: Final answer
    x = 119.70

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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.