Finding the Fourth Proportional to 111.72, 153.99 and 78.93

Step by Step Solution

1. Step 1: Write the proportion equation
   111.72 : 153.99 = 78.93 : x
2. Step 2: Convert to fraction form
   111.72/153.99 = 78.93/x
3. Step 3: Cross multiply
   111.72x = 153.99 × 78.93
4. Step 4: Simplify right side
   111.72x = 12,154.43
5. Step 5: Solve for x
   x = 12,154.43/111.72
6. Step 6: Final answer
   x = 108.79