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Finding the Fourth Proportional to 136.78, 188.70 and 85

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Solution

The fourth proportional to 136.78, 188.70 and 85 is: 117.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    136.78 : 188.70 = 85 : x
  2. Step 2: Convert to fraction form
    136.78/188.70 = 85/x
  3. Step 3: Cross multiply
    136.78x = 188.70 × 85
  4. Step 4: Simplify right side
    136.78x = 16,039.50
  5. Step 5: Solve for x
    x = 16,039.50/136.78
  6. Step 6: Final answer
    x = 117.26

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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.