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Finding the Fourth Proportional to 86.26, 119.09 and 78

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Solution

The fourth proportional to 86.26, 119.09 and 78 is: 107.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.26 : 119.09 = 78 : x
  2. Step 2: Convert to fraction form
    86.26/119.09 = 78/x
  3. Step 3: Cross multiply
    86.26x = 119.09 × 78
  4. Step 4: Simplify right side
    86.26x = 9,288.63
  5. Step 5: Solve for x
    x = 9,288.63/86.26
  6. Step 6: Final answer
    x = 107.69

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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.