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Finding the Fourth Proportional to 122.78, 183.96 and 86.64

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Solution

The fourth proportional to 122.78, 183.96 and 86.64 is: 129.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.78 : 183.96 = 86.64 : x
  2. Step 2: Convert to fraction form
    122.78/183.96 = 86.64/x
  3. Step 3: Cross multiply
    122.78x = 183.96 × 86.64
  4. Step 4: Simplify right side
    122.78x = 15,938.29
  5. Step 5: Solve for x
    x = 15,938.29/122.78
  6. Step 6: Final answer
    x = 129.82

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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.