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Finding the Fourth Proportional to 86.91, 119.67 and 77.69

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Solution

The fourth proportional to 86.91, 119.67 and 77.69 is: 106.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.91 : 119.67 = 77.69 : x
  2. Step 2: Convert to fraction form
    86.91/119.67 = 77.69/x
  3. Step 3: Cross multiply
    86.91x = 119.67 × 77.69
  4. Step 4: Simplify right side
    86.91x = 9,297.60
  5. Step 5: Solve for x
    x = 9,297.60/86.91
  6. Step 6: Final answer
    x = 106.99

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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.