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Finding the Fourth Proportional to 138.89, 191.66 and 76.71

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Solution

The fourth proportional to 138.89, 191.66 and 76.71 is: 105.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.89 : 191.66 = 76.71 : x
  2. Step 2: Convert to fraction form
    138.89/191.66 = 76.71/x
  3. Step 3: Cross multiply
    138.89x = 191.66 × 76.71
  4. Step 4: Simplify right side
    138.89x = 14,702.65
  5. Step 5: Solve for x
    x = 14,702.65/138.89
  6. Step 6: Final answer
    x = 105.86

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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.