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Finding the Fourth Proportional to 121.20, 181.45 and 86.77

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Solution

The fourth proportional to 121.20, 181.45 and 86.77 is: 129.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.20 : 181.45 = 86.77 : x
  2. Step 2: Convert to fraction form
    121.20/181.45 = 86.77/x
  3. Step 3: Cross multiply
    121.20x = 181.45 × 86.77
  4. Step 4: Simplify right side
    121.20x = 15,744.42
  5. Step 5: Solve for x
    x = 15,744.42/121.20
  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.