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Finding the Fourth Proportional to 21.81, 30.11 and 15.36

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Solution

The fourth proportional to 21.81, 30.11 and 15.36 is: 21.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.81 : 30.11 = 15.36 : x
  2. Step 2: Convert to fraction form
    21.81/30.11 = 15.36/x
  3. Step 3: Cross multiply
    21.81x = 30.11 × 15.36
  4. Step 4: Simplify right side
    21.81x = 462.49
  5. Step 5: Solve for x
    x = 462.49/21.81
  6. Step 6: Final answer
    x = 21.21

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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.