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Finding the Fourth Proportional to 21.87, 29.97 and 21.78

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Solution

The fourth proportional to 21.87, 29.97 and 21.78 is: 29.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.87 : 29.97 = 21.78 : x
  2. Step 2: Convert to fraction form
    21.87/29.97 = 21.78/x
  3. Step 3: Cross multiply
    21.87x = 29.97 × 21.78
  4. Step 4: Simplify right side
    21.87x = 652.75
  5. Step 5: Solve for x
    x = 652.75/21.87
  6. Step 6: Final answer
    x = 29.85

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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.