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Finding the Fourth Proportional to 13.18, 19.76 and 8.61

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Solution

The fourth proportional to 13.18, 19.76 and 8.61 is: 12.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.18 : 19.76 = 8.61 : x
  2. Step 2: Convert to fraction form
    13.18/19.76 = 8.61/x
  3. Step 3: Cross multiply
    13.18x = 19.76 × 8.61
  4. Step 4: Simplify right side
    13.18x = 170.13
  5. Step 5: Solve for x
    x = 170.13/13.18
  6. Step 6: Final answer
    x = 12.91

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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.