Finding the Fourth Proportional to 111.33, 153.72 and 78.57

Step by Step Solution

1. Step 1: Write the proportion equation
   111.33 : 153.72 = 78.57 : x
2. Step 2: Convert to fraction form
   111.33/153.72 = 78.57/x
3. Step 3: Cross multiply
   111.33x = 153.72 × 78.57
4. Step 4: Simplify right side
   111.33x = 12,077.78
5. Step 5: Solve for x
   x = 12,077.78/111.33
6. Step 6: Final answer
   x = 108.49