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Finding the Fourth Proportional to 15.80, 21.78 and 11.92

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Solution

The fourth proportional to 15.80, 21.78 and 11.92 is: 16.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.80 : 21.78 = 11.92 : x
  2. Step 2: Convert to fraction form
    15.80/21.78 = 11.92/x
  3. Step 3: Cross multiply
    15.80x = 21.78 × 11.92
  4. Step 4: Simplify right side
    15.80x = 259.62
  5. Step 5: Solve for x
    x = 259.62/15.80
  6. Step 6: Final answer
    x = 16.43

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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.