Finding the Fourth Proportional to 111.88, 154.33 and 80.78

Step by Step Solution

1. Step 1: Write the proportion equation
   111.88 : 154.33 = 80.78 : x
2. Step 2: Convert to fraction form
   111.88/154.33 = 80.78/x
3. Step 3: Cross multiply
   111.88x = 154.33 × 80.78
4. Step 4: Simplify right side
   111.88x = 12,466.78
5. Step 5: Solve for x
   x = 12,466.78/111.88
6. Step 6: Final answer
   x = 111.43