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Finding the Fourth Proportional to 138.79, 191.79 and 99.91

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Solution

The fourth proportional to 138.79, 191.79 and 99.91 is: 138.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.79 : 191.79 = 99.91 : x
  2. Step 2: Convert to fraction form
    138.79/191.79 = 99.91/x
  3. Step 3: Cross multiply
    138.79x = 191.79 × 99.91
  4. Step 4: Simplify right side
    138.79x = 19,161.74
  5. Step 5: Solve for x
    x = 19,161.74/138.79
  6. Step 6: Final answer
    x = 138.06

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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.