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Finding the Fourth Proportional to 7.91, 10.85 and 7.22

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Solution

The fourth proportional to 7.91, 10.85 and 7.22 is: 9.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    7.91 : 10.85 = 7.22 : x
  2. Step 2: Convert to fraction form
    7.91/10.85 = 7.22/x
  3. Step 3: Cross multiply
    7.91x = 10.85 × 7.22
  4. Step 4: Simplify right side
    7.91x = 78.25
  5. Step 5: Solve for x
    x = 78.25/7.91
  6. Step 6: Final answer
    x = 9.90

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.