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Finding the Fourth Proportional to 20.90, 28.72 and 19.64

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Solution

The fourth proportional to 20.90, 28.72 and 19.64 is: 26.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.90 : 28.72 = 19.64 : x
  2. Step 2: Convert to fraction form
    20.90/28.72 = 19.64/x
  3. Step 3: Cross multiply
    20.90x = 28.72 × 19.64
  4. Step 4: Simplify right side
    20.90x = 564.06
  5. Step 5: Solve for x
    x = 564.06/20.90
  6. Step 6: Final answer
    x = 26.99

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.