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Finding the Fourth Proportional to 9.31, 12.81 and 7.69

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Solution

The fourth proportional to 9.31, 12.81 and 7.69 is: 10.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    9.31 : 12.81 = 7.69 : x
  2. Step 2: Convert to fraction form
    9.31/12.81 = 7.69/x
  3. Step 3: Cross multiply
    9.31x = 12.81 × 7.69
  4. Step 4: Simplify right side
    9.31x = 98.51
  5. Step 5: Solve for x
    x = 98.51/9.31
  6. Step 6: Final answer
    x = 10.58

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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.