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Finding the Fourth Proportional to 28.98, 39.98 and 21.72

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Solution

The fourth proportional to 28.98, 39.98 and 21.72 is: 29.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.98 : 39.98 = 21.72 : x
  2. Step 2: Convert to fraction form
    28.98/39.98 = 21.72/x
  3. Step 3: Cross multiply
    28.98x = 39.98 × 21.72
  4. Step 4: Simplify right side
    28.98x = 868.42
  5. Step 5: Solve for x
    x = 868.42/28.98
  6. Step 6: Final answer
    x = 29.97

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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.