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Finding the Fourth Proportional to 86.05, 118.74 and 78.76

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Solution

The fourth proportional to 86.05, 118.74 and 78.76 is: 108.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.05 : 118.74 = 78.76 : x
  2. Step 2: Convert to fraction form
    86.05/118.74 = 78.76/x
  3. Step 3: Cross multiply
    86.05x = 118.74 × 78.76
  4. Step 4: Simplify right side
    86.05x = 9,351.96
  5. Step 5: Solve for x
    x = 9,351.96/86.05
  6. Step 6: Final answer
    x = 108.68

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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.