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Finding the Fourth Proportional to 20.90, 31.22 and 18.58

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Solution

The fourth proportional to 20.90, 31.22 and 18.58 is: 27.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.90 : 31.22 = 18.58 : x
  2. Step 2: Convert to fraction form
    20.90/31.22 = 18.58/x
  3. Step 3: Cross multiply
    20.90x = 31.22 × 18.58
  4. Step 4: Simplify right side
    20.90x = 579.97
  5. Step 5: Solve for x
    x = 579.97/20.90
  6. Step 6: Final answer
    x = 27.75

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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.