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Finding the Fourth Proportional to 99.97, 138.20 and 79.39

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Solution

The fourth proportional to 99.97, 138.20 and 79.39 is: 109.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.97 : 138.20 = 79.39 : x
  2. Step 2: Convert to fraction form
    99.97/138.20 = 79.39/x
  3. Step 3: Cross multiply
    99.97x = 138.20 × 79.39
  4. Step 4: Simplify right side
    99.97x = 10,971.70
  5. Step 5: Solve for x
    x = 10,971.70/99.97
  6. Step 6: Final answer
    x = 109.75

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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.