Finding the Fourth Proportional to 111.92, 154.33 and 78.72

Step by Step Solution

1. Step 1: Write the proportion equation
   111.92 : 154.33 = 78.72 : x
2. Step 2: Convert to fraction form
   111.92/154.33 = 78.72/x
3. Step 3: Cross multiply
   111.92x = 154.33 × 78.72
4. Step 4: Simplify right side
   111.92x = 12,147.69
5. Step 5: Solve for x
   x = 12,147.69/111.92
6. Step 6: Final answer
   x = 108.54