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Finding the Fourth Proportional to 21.61, 29.81 and 12.86

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Solution

The fourth proportional to 21.61, 29.81 and 12.86 is: 17.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.61 : 29.81 = 12.86 : x
  2. Step 2: Convert to fraction form
    21.61/29.81 = 12.86/x
  3. Step 3: Cross multiply
    21.61x = 29.81 × 12.86
  4. Step 4: Simplify right side
    21.61x = 383.27
  5. Step 5: Solve for x
    x = 383.27/21.61
  6. Step 6: Final answer
    x = 17.74

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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.