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Finding the Fourth Proportional to 20.89, 31.32 and 19.81

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Solution

The fourth proportional to 20.89, 31.32 and 19.81 is: 29.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.89 : 31.32 = 19.81 : x
  2. Step 2: Convert to fraction form
    20.89/31.32 = 19.81/x
  3. Step 3: Cross multiply
    20.89x = 31.32 × 19.81
  4. Step 4: Simplify right side
    20.89x = 620.45
  5. Step 5: Solve for x
    x = 620.45/20.89
  6. Step 6: Final answer
    x = 29.70

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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.