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Finding the Fourth Proportional to 120.15, 180.15 and 81.15

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Solution

The fourth proportional to 120.15, 180.15 and 81.15 is: 121.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.15 : 180.15 = 81.15 : x
  2. Step 2: Convert to fraction form
    120.15/180.15 = 81.15/x
  3. Step 3: Cross multiply
    120.15x = 180.15 × 81.15
  4. Step 4: Simplify right side
    120.15x = 14,618.29
  5. Step 5: Solve for x
    x = 14,618.29/120.15
  6. Step 6: Final answer
    x = 121.67

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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.