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Finding the Fourth Proportional to 28.79, 39.71 and 20.61

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Solution

The fourth proportional to 28.79, 39.71 and 20.61 is: 28.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.79 : 39.71 = 20.61 : x
  2. Step 2: Convert to fraction form
    28.79/39.71 = 20.61/x
  3. Step 3: Cross multiply
    28.79x = 39.71 × 20.61
  4. Step 4: Simplify right side
    28.79x = 818.32
  5. Step 5: Solve for x
    x = 818.32/28.79
  6. Step 6: Final answer
    x = 28.43

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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.