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Finding the Fourth Proportional to 21.30, 31.98 and 20.58

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Solution

The fourth proportional to 21.30, 31.98 and 20.58 is: 30.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.30 : 31.98 = 20.58 : x
  2. Step 2: Convert to fraction form
    21.30/31.98 = 20.58/x
  3. Step 3: Cross multiply
    21.30x = 31.98 × 20.58
  4. Step 4: Simplify right side
    21.30x = 658.15
  5. Step 5: Solve for x
    x = 658.15/21.30
  6. Step 6: Final answer
    x = 30.90

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.