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Finding the Fourth Proportional to 28.86, 39.79 and 21.11

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Solution

The fourth proportional to 28.86, 39.79 and 21.11 is: 29.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.86 : 39.79 = 21.11 : x
  2. Step 2: Convert to fraction form
    28.86/39.79 = 21.11/x
  3. Step 3: Cross multiply
    28.86x = 39.79 × 21.11
  4. Step 4: Simplify right side
    28.86x = 840.02
  5. Step 5: Solve for x
    x = 840.02/28.86
  6. Step 6: Final answer
    x = 29.11

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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.