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Finding the Fourth Proportional to 99.90, 138.11 and 79.38

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Solution

The fourth proportional to 99.90, 138.11 and 79.38 is: 109.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.90 : 138.11 = 79.38 : x
  2. Step 2: Convert to fraction form
    99.90/138.11 = 79.38/x
  3. Step 3: Cross multiply
    99.90x = 138.11 × 79.38
  4. Step 4: Simplify right side
    99.90x = 10,962.77
  5. Step 5: Solve for x
    x = 10,962.77/99.90
  6. Step 6: Final answer
    x = 109.74

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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.