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Finding the Fourth Proportional to 138.18, 206.79 and 99.74

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Solution

The fourth proportional to 138.18, 206.79 and 99.74 is: 149.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.18 : 206.79 = 99.74 : x
  2. Step 2: Convert to fraction form
    138.18/206.79 = 99.74/x
  3. Step 3: Cross multiply
    138.18x = 206.79 × 99.74
  4. Step 4: Simplify right side
    138.18x = 20,625.38
  5. Step 5: Solve for x
    x = 20,625.38/138.18
  6. Step 6: Final answer
    x = 149.26

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.