Finding the Fourth Proportional to 111.27, 153.60 and 78.09

Step by Step Solution

1. Step 1: Write the proportion equation
   111.27 : 153.60 = 78.09 : x
2. Step 2: Convert to fraction form
   111.27/153.60 = 78.09/x
3. Step 3: Cross multiply
   111.27x = 153.60 × 78.09
4. Step 4: Simplify right side
   111.27x = 11,994.62
5. Step 5: Solve for x
   x = 11,994.62/111.27
6. Step 6: Final answer
   x = 107.80