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Finding the Fourth Proportional to 20.15, 27.79 and 17.21

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Solution

The fourth proportional to 20.15, 27.79 and 17.21 is: 23.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.15 : 27.79 = 17.21 : x
  2. Step 2: Convert to fraction form
    20.15/27.79 = 17.21/x
  3. Step 3: Cross multiply
    20.15x = 27.79 × 17.21
  4. Step 4: Simplify right side
    20.15x = 478.39
  5. Step 5: Solve for x
    x = 478.39/20.15
  6. Step 6: Final answer
    x = 23.74

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.