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Finding the Fourth Proportional to 20.89, 31.18 and 18.05

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Solution

The fourth proportional to 20.89, 31.18 and 18.05 is: 26.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.89 : 31.18 = 18.05 : x
  2. Step 2: Convert to fraction form
    20.89/31.18 = 18.05/x
  3. Step 3: Cross multiply
    20.89x = 31.18 × 18.05
  4. Step 4: Simplify right side
    20.89x = 562.83
  5. Step 5: Solve for x
    x = 562.83/20.89
  6. Step 6: Final answer
    x = 26.95

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.