Finding the Fourth Proportional to 91.81, 137.85 and 76.69

Step by Step Solution

1. Step 1: Write the proportion equation
   91.81 : 137.85 = 76.69 : x
2. Step 2: Convert to fraction form
   91.81/137.85 = 76.69/x
3. Step 3: Cross multiply
   91.81x = 137.85 × 76.69
4. Step 4: Simplify right side
   91.81x = 10,571.72
5. Step 5: Solve for x
   x = 10,571.72/91.81
6. Step 6: Final answer
   x = 115.15