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Finding the Fourth Proportional to 15.81, 21.83 and 8.91

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Solution

The fourth proportional to 15.81, 21.83 and 8.91 is: 12.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.81 : 21.83 = 8.91 : x
  2. Step 2: Convert to fraction form
    15.81/21.83 = 8.91/x
  3. Step 3: Cross multiply
    15.81x = 21.83 × 8.91
  4. Step 4: Simplify right side
    15.81x = 194.38
  5. Step 5: Solve for x
    x = 194.38/15.81
  6. Step 6: Final answer
    x = 12.29

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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.