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Finding the Fourth Proportional to 21.49, 29.81 and 20.65

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Solution

The fourth proportional to 21.49, 29.81 and 20.65 is: 28.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.49 : 29.81 = 20.65 : x
  2. Step 2: Convert to fraction form
    21.49/29.81 = 20.65/x
  3. Step 3: Cross multiply
    21.49x = 29.81 × 20.65
  4. Step 4: Simplify right side
    21.49x = 615.58
  5. Step 5: Solve for x
    x = 615.58/21.49
  6. Step 6: Final answer
    x = 28.64

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.