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Finding the Fourth Proportional to 20.80, 31.20 and 11.67

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Solution

The fourth proportional to 20.80, 31.20 and 11.67 is: 17.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.80 : 31.20 = 11.67 : x
  2. Step 2: Convert to fraction form
    20.80/31.20 = 11.67/x
  3. Step 3: Cross multiply
    20.80x = 31.20 × 11.67
  4. Step 4: Simplify right side
    20.80x = 364.10
  5. Step 5: Solve for x
    x = 364.10/20.80
  6. Step 6: Final answer
    x = 17.51

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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.