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Finding the Fourth Proportional to 8.15, 12.21 and 5.15

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Solution

The fourth proportional to 8.15, 12.21 and 5.15 is: 7.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    8.15 : 12.21 = 5.15 : x
  2. Step 2: Convert to fraction form
    8.15/12.21 = 5.15/x
  3. Step 3: Cross multiply
    8.15x = 12.21 × 5.15
  4. Step 4: Simplify right side
    8.15x = 62.82
  5. Step 5: Solve for x
    x = 62.82/8.15
  6. Step 6: Final answer
    x = 7.71

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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.