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Finding the Fourth Proportional to 92.10, 138.15 and 31.21

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Solution

The fourth proportional to 92.10, 138.15 and 31.21 is: 46.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    92.10 : 138.15 = 31.21 : x
  2. Step 2: Convert to fraction form
    92.10/138.15 = 31.21/x
  3. Step 3: Cross multiply
    92.10x = 138.15 × 31.21
  4. Step 4: Simplify right side
    92.10x = 4,311.66
  5. Step 5: Solve for x
    x = 4,311.66/92.10
  6. Step 6: Final answer
    x = 46.82

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.