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Finding the Third Proportional to 90 and 138.38

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Solution

The third proportional to 90 and 138.38 is: 212.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    90 : 138.38 = 138.38 : x
  2. Step 2: Convert to fraction form
    90/138.38 = 138.38/x
  3. Step 3: Cross multiply
    90x = 138.38 × 138.38
  4. Step 4: Simplify right side
    90x = 19,147.64
  5. Step 5: Solve for x
    x = 19,147.64/90
  6. Step 6: Final answer
    x = 212.75

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Why These Related Problems?

These problems maintain the same ratio (1.54) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.