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Finding the Fourth Proportional to 11.20, 15.45 and 8.78

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Solution

The fourth proportional to 11.20, 15.45 and 8.78 is: 12.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    11.20 : 15.45 = 8.78 : x
  2. Step 2: Convert to fraction form
    11.20/15.45 = 8.78/x
  3. Step 3: Cross multiply
    11.20x = 15.45 × 8.78
  4. Step 4: Simplify right side
    11.20x = 135.65
  5. Step 5: Solve for x
    x = 135.65/11.20
  6. Step 6: Final answer
    x = 12.11

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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.