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Finding the Fourth Proportional to 138.60, 190.80 and 122.40

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Solution

The fourth proportional to 138.60, 190.80 and 122.40 is: 168.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.60 : 190.80 = 122.40 : x
  2. Step 2: Convert to fraction form
    138.60/190.80 = 122.40/x
  3. Step 3: Cross multiply
    138.60x = 190.80 × 122.40
  4. Step 4: Simplify right side
    138.60x = 23,353.92
  5. Step 5: Solve for x
    x = 23,353.92/138.60
  6. Step 6: Final answer
    x = 168.50

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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.