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Finding the Fourth Proportional to 21.56, 29.75 and 12.82

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Solution

The fourth proportional to 21.56, 29.75 and 12.82 is: 17.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.56 : 29.75 = 12.82 : x
  2. Step 2: Convert to fraction form
    21.56/29.75 = 12.82/x
  3. Step 3: Cross multiply
    21.56x = 29.75 × 12.82
  4. Step 4: Simplify right side
    21.56x = 381.40
  5. Step 5: Solve for x
    x = 381.40/21.56
  6. Step 6: Final answer
    x = 17.69

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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.