Finding the Fourth Proportional to 111.05, 153.42 and 78.45

Step by Step Solution

1. Step 1: Write the proportion equation
   111.05 : 153.42 = 78.45 : x
2. Step 2: Convert to fraction form
   111.05/153.42 = 78.45/x
3. Step 3: Cross multiply
   111.05x = 153.42 × 78.45
4. Step 4: Simplify right side
   111.05x = 12,035.80
5. Step 5: Solve for x
   x = 12,035.80/111.05
6. Step 6: Final answer
   x = 108.39