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Finding the Fourth Proportional to 138.89, 191.65 and 76.72

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Solution

The fourth proportional to 138.89, 191.65 and 76.72 is: 105.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.89 : 191.65 = 76.72 : x
  2. Step 2: Convert to fraction form
    138.89/191.65 = 76.72/x
  3. Step 3: Cross multiply
    138.89x = 191.65 × 76.72
  4. Step 4: Simplify right side
    138.89x = 14,702.91
  5. Step 5: Solve for x
    x = 14,702.91/138.89
  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.