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Finding the Fourth Proportional to 21.06, 28.98 and 20.39

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Solution

The fourth proportional to 21.06, 28.98 and 20.39 is: 28.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.06 : 28.98 = 20.39 : x
  2. Step 2: Convert to fraction form
    21.06/28.98 = 20.39/x
  3. Step 3: Cross multiply
    21.06x = 28.98 × 20.39
  4. Step 4: Simplify right side
    21.06x = 590.76
  5. Step 5: Solve for x
    x = 590.76/21.06
  6. Step 6: Final answer
    x = 28.05

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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.