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Finding the Fourth Proportional to 28.78, 39.69 and 20.59

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Solution

The fourth proportional to 28.78, 39.69 and 20.59 is: 28.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.78 : 39.69 = 20.59 : x
  2. Step 2: Convert to fraction form
    28.78/39.69 = 20.59/x
  3. Step 3: Cross multiply
    28.78x = 39.69 × 20.59
  4. Step 4: Simplify right side
    28.78x = 817.22
  5. Step 5: Solve for x
    x = 817.22/28.78
  6. Step 6: Final answer
    x = 28.40

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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.