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Finding the Fourth Proportional to 7.91, 11.81 and 7.78

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Solution

The fourth proportional to 7.91, 11.81 and 7.78 is: 11.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    7.91 : 11.81 = 7.78 : x
  2. Step 2: Convert to fraction form
    7.91/11.81 = 7.78/x
  3. Step 3: Cross multiply
    7.91x = 11.81 × 7.78
  4. Step 4: Simplify right side
    7.91x = 91.88
  5. Step 5: Solve for x
    x = 91.88/7.91
  6. Step 6: Final answer
    x = 11.62

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.