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Finding the Fourth Proportional to 138, 190.40 and 82.71

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Solution

The fourth proportional to 138, 190.40 and 82.71 is: 114.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    138 : 190.40 = 82.71 : x
  2. Step 2: Convert to fraction form
    138/190.40 = 82.71/x
  3. Step 3: Cross multiply
    138x = 190.40 × 82.71
  4. Step 4: Simplify right side
    138x = 15,747.98
  5. Step 5: Solve for x
    x = 15,747.98/138
  6. Step 6: Final answer
    x = 114.12

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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.