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Finding the Fourth Proportional to 20.15, 27.80 and 11.85

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Solution

The fourth proportional to 20.15, 27.80 and 11.85 is: 16.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.15 : 27.80 = 11.85 : x
  2. Step 2: Convert to fraction form
    20.15/27.80 = 11.85/x
  3. Step 3: Cross multiply
    20.15x = 27.80 × 11.85
  4. Step 4: Simplify right side
    20.15x = 329.46
  5. Step 5: Solve for x
    x = 329.46/20.15
  6. Step 6: Final answer
    x = 16.35

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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.