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Finding the Fourth Proportional to 86.78, 119.67 and 81.02

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Solution

The fourth proportional to 86.78, 119.67 and 81.02 is: 111.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.78 : 119.67 = 81.02 : x
  2. Step 2: Convert to fraction form
    86.78/119.67 = 81.02/x
  3. Step 3: Cross multiply
    86.78x = 119.67 × 81.02
  4. Step 4: Simplify right side
    86.78x = 9,695.66
  5. Step 5: Solve for x
    x = 9,695.66/86.78
  6. Step 6: Final answer
    x = 111.73

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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.