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Finding the Fourth Proportional to 138.69, 208.08 and 90.54

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Solution

The fourth proportional to 138.69, 208.08 and 90.54 is: 135.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.69 : 208.08 = 90.54 : x
  2. Step 2: Convert to fraction form
    138.69/208.08 = 90.54/x
  3. Step 3: Cross multiply
    138.69x = 208.08 × 90.54
  4. Step 4: Simplify right side
    138.69x = 18,839.56
  5. Step 5: Solve for x
    x = 18,839.56/138.69
  6. Step 6: Final answer
    x = 135.84

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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.