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Finding the Fourth Proportional to 21.23, 31.81 and 12.66

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Solution

The fourth proportional to 21.23, 31.81 and 12.66 is: 18.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.23 : 31.81 = 12.66 : x
  2. Step 2: Convert to fraction form
    21.23/31.81 = 12.66/x
  3. Step 3: Cross multiply
    21.23x = 31.81 × 12.66
  4. Step 4: Simplify right side
    21.23x = 402.71
  5. Step 5: Solve for x
    x = 402.71/21.23
  6. Step 6: Final answer
    x = 18.97

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.