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Finding the Fourth Proportional to 20.69, 30.90 and 17.80

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Solution

The fourth proportional to 20.69, 30.90 and 17.80 is: 26.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.69 : 30.90 = 17.80 : x
  2. Step 2: Convert to fraction form
    20.69/30.90 = 17.80/x
  3. Step 3: Cross multiply
    20.69x = 30.90 × 17.80
  4. Step 4: Simplify right side
    20.69x = 550.02
  5. Step 5: Solve for x
    x = 550.02/20.69
  6. Step 6: Final answer
    x = 26.58

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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.