Finding the Fourth Proportional to 111.63, 154.06 and 78.42

Step by Step Solution

1. Step 1: Write the proportion equation
   111.63 : 154.06 = 78.42 : x
2. Step 2: Convert to fraction form
   111.63/154.06 = 78.42/x
3. Step 3: Cross multiply
   111.63x = 154.06 × 78.42
4. Step 4: Simplify right side
   111.63x = 12,081.19
5. Step 5: Solve for x
   x = 12,081.19/111.63
6. Step 6: Final answer
   x = 108.23