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Finding the Fourth Proportional to 120.85, 181.38 and 86.51

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Solution

The fourth proportional to 120.85, 181.38 and 86.51 is: 129.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.85 : 181.38 = 86.51 : x
  2. Step 2: Convert to fraction form
    120.85/181.38 = 86.51/x
  3. Step 3: Cross multiply
    120.85x = 181.38 × 86.51
  4. Step 4: Simplify right side
    120.85x = 15,691.18
  5. Step 5: Solve for x
    x = 15,691.18/120.85
  6. Step 6: Final answer
    x = 129.84

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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.