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Finding the Fourth Proportional to 8.15, 12.15 and 7.85

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Solution

The fourth proportional to 8.15, 12.15 and 7.85 is: 11.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    8.15 : 12.15 = 7.85 : x
  2. Step 2: Convert to fraction form
    8.15/12.15 = 7.85/x
  3. Step 3: Cross multiply
    8.15x = 12.15 × 7.85
  4. Step 4: Simplify right side
    8.15x = 95.38
  5. Step 5: Solve for x
    x = 95.38/8.15
  6. Step 6: Final answer
    x = 11.70

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.