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Finding the Fourth Proportional to 21.54, 29.71 and 12.91

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Solution

The fourth proportional to 21.54, 29.71 and 12.91 is: 17.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.54 : 29.71 = 12.91 : x
  2. Step 2: Convert to fraction form
    21.54/29.71 = 12.91/x
  3. Step 3: Cross multiply
    21.54x = 29.71 × 12.91
  4. Step 4: Simplify right side
    21.54x = 383.56
  5. Step 5: Solve for x
    x = 383.56/21.54
  6. Step 6: Final answer
    x = 17.81

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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.