Finding the Fourth Proportional to 111.61, 154.02 and 78.82

Step by Step Solution

1. Step 1: Write the proportion equation
   111.61 : 154.02 = 78.82 : x
2. Step 2: Convert to fraction form
   111.61/154.02 = 78.82/x
3. Step 3: Cross multiply
   111.61x = 154.02 × 78.82
4. Step 4: Simplify right side
   111.61x = 12,139.86
5. Step 5: Solve for x
   x = 12,139.86/111.61
6. Step 6: Final answer
   x = 108.77