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Finding the Fourth Proportional to 28.26, 39 and 21.78

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Solution

The fourth proportional to 28.26, 39 and 21.78 is: 30.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.26 : 39 = 21.78 : x
  2. Step 2: Convert to fraction form
    28.26/39 = 21.78/x
  3. Step 3: Cross multiply
    28.26x = 39 × 21.78
  4. Step 4: Simplify right side
    28.26x = 849.42
  5. Step 5: Solve for x
    x = 849.42/28.26
  6. Step 6: Final answer
    x = 30.06

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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.