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Finding the Fourth Proportional to 138.13, 206.78 and 127.31

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Solution

The fourth proportional to 138.13, 206.78 and 127.31 is: 190.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.13 : 206.78 = 127.31 : x
  2. Step 2: Convert to fraction form
    138.13/206.78 = 127.31/x
  3. Step 3: Cross multiply
    138.13x = 206.78 × 127.31
  4. Step 4: Simplify right side
    138.13x = 26,323.49
  5. Step 5: Solve for x
    x = 26,323.49/138.13
  6. Step 6: Final answer
    x = 190.57

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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.