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Finding the Fourth Proportional to 138.91, 191.69 and 76.74

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Solution

The fourth proportional to 138.91, 191.69 and 76.74 is: 105.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.91 : 191.69 = 76.74 : x
  2. Step 2: Convert to fraction form
    138.91/191.69 = 76.74/x
  3. Step 3: Cross multiply
    138.91x = 191.69 × 76.74
  4. Step 4: Simplify right side
    138.91x = 14,710.48
  5. Step 5: Solve for x
    x = 14,710.48/138.91
  6. Step 6: Final answer
    x = 105.90

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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.