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Finding the Fourth Proportional to 20.89, 31.31 and 13.17

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Solution

The fourth proportional to 20.89, 31.31 and 13.17 is: 19.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.89 : 31.31 = 13.17 : x
  2. Step 2: Convert to fraction form
    20.89/31.31 = 13.17/x
  3. Step 3: Cross multiply
    20.89x = 31.31 × 13.17
  4. Step 4: Simplify right side
    20.89x = 412.35
  5. Step 5: Solve for x
    x = 412.35/20.89
  6. Step 6: Final answer
    x = 19.74

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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.