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Finding the Fourth Proportional to 20.89, 31.34 and 20.78

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Solution

The fourth proportional to 20.89, 31.34 and 20.78 is: 31.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.89 : 31.34 = 20.78 : x
  2. Step 2: Convert to fraction form
    20.89/31.34 = 20.78/x
  3. Step 3: Cross multiply
    20.89x = 31.34 × 20.78
  4. Step 4: Simplify right side
    20.89x = 651.38
  5. Step 5: Solve for x
    x = 651.38/20.89
  6. Step 6: Final answer
    x = 31.19

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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.