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Finding the Fourth Proportional to 21.78, 29.89 and 21.78

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Solution

The fourth proportional to 21.78, 29.89 and 21.78 is: 29.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.78 : 29.89 = 21.78 : x
  2. Step 2: Convert to fraction form
    21.78/29.89 = 21.78/x
  3. Step 3: Cross multiply
    21.78x = 29.89 × 21.78
  4. Step 4: Simplify right side
    21.78x = 651.00
  5. Step 5: Solve for x
    x = 651.00/21.78
  6. Step 6: Final answer
    x = 29.89

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.