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Finding the Fourth Proportional to 121.11, 181.46 and 86.70

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Solution

The fourth proportional to 121.11, 181.46 and 86.70 is: 129.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.11 : 181.46 = 86.70 : x
  2. Step 2: Convert to fraction form
    121.11/181.46 = 86.70/x
  3. Step 3: Cross multiply
    121.11x = 181.46 × 86.70
  4. Step 4: Simplify right side
    121.11x = 15,732.99
  5. Step 5: Solve for x
    x = 15,732.99/121.11
  6. Step 6: Final answer
    x = 129.90

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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.