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Finding the Fourth Proportional to 122.88, 183.78 and 86.70

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Solution

The fourth proportional to 122.88, 183.78 and 86.70 is: 129.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.88 : 183.78 = 86.70 : x
  2. Step 2: Convert to fraction form
    122.88/183.78 = 86.70/x
  3. Step 3: Cross multiply
    122.88x = 183.78 × 86.70
  4. Step 4: Simplify right side
    122.88x = 15,933.73
  5. Step 5: Solve for x
    x = 15,933.73/122.88
  6. Step 6: Final answer
    x = 129.67

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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.