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Finding the Fourth Proportional to 21.81, 30.08 and 20.05

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Solution

The fourth proportional to 21.81, 30.08 and 20.05 is: 27.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.81 : 30.08 = 20.05 : x
  2. Step 2: Convert to fraction form
    21.81/30.08 = 20.05/x
  3. Step 3: Cross multiply
    21.81x = 30.08 × 20.05
  4. Step 4: Simplify right side
    21.81x = 603.19
  5. Step 5: Solve for x
    x = 603.19/21.81
  6. Step 6: Final answer
    x = 27.66

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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.