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Finding the Fourth Proportional to 21.98, 30.18 and 21.05

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Solution

The fourth proportional to 21.98, 30.18 and 21.05 is: 28.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.98 : 30.18 = 21.05 : x
  2. Step 2: Convert to fraction form
    21.98/30.18 = 21.05/x
  3. Step 3: Cross multiply
    21.98x = 30.18 × 21.05
  4. Step 4: Simplify right side
    21.98x = 635.08
  5. Step 5: Solve for x
    x = 635.08/21.98
  6. Step 6: Final answer
    x = 28.89

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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.