Finding the Fourth Proportional to 111.89, 154.49 and 78.77

Step by Step Solution

1. Step 1: Write the proportion equation
   111.89 : 154.49 = 78.77 : x
2. Step 2: Convert to fraction form
   111.89/154.49 = 78.77/x
3. Step 3: Cross multiply
   111.89x = 154.49 × 78.77
4. Step 4: Simplify right side
   111.89x = 12,168.01
5. Step 5: Solve for x
   x = 12,168.01/111.89
6. Step 6: Final answer
   x = 108.75