Finding the Fourth Proportional to 111.62, 154.07 and 78.81

Step by Step Solution

1. Step 1: Write the proportion equation
   111.62 : 154.07 = 78.81 : x
2. Step 2: Convert to fraction form
   111.62/154.07 = 78.81/x
3. Step 3: Cross multiply
   111.62x = 154.07 × 78.81
4. Step 4: Simplify right side
   111.62x = 12,141.86
5. Step 5: Solve for x
   x = 12,141.86/111.62
6. Step 6: Final answer
   x = 108.78