Finding the Fourth Proportional to 111.12, 153.24 and 78.42

Step by Step Solution

1. Step 1: Write the proportion equation
   111.12 : 153.24 = 78.42 : x
2. Step 2: Convert to fraction form
   111.12/153.24 = 78.42/x
3. Step 3: Cross multiply
   111.12x = 153.24 × 78.42
4. Step 4: Simplify right side
   111.12x = 12,017.08
5. Step 5: Solve for x
   x = 12,017.08/111.12
6. Step 6: Final answer
   x = 108.15