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Finding the Fourth Proportional to 5, 6.91 and 3.92

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Solution

The fourth proportional to 5, 6.91 and 3.92 is: 5.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    5 : 6.91 = 3.92 : x
  2. Step 2: Convert to fraction form
    5/6.91 = 3.92/x
  3. Step 3: Cross multiply
    5x = 6.91 × 3.92
  4. Step 4: Simplify right side
    5x = 27.09
  5. Step 5: Solve for x
    x = 27.09/5
  6. Step 6: Final answer
    x = 5.42

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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.