Finding the Fourth Proportional to 111.43, 153.80 and 78.69

Step by Step Solution

1. Step 1: Write the proportion equation
   111.43 : 153.80 = 78.69 : x
2. Step 2: Convert to fraction form
   111.43/153.80 = 78.69/x
3. Step 3: Cross multiply
   111.43x = 153.80 × 78.69
4. Step 4: Simplify right side
   111.43x = 12,102.52
5. Step 5: Solve for x
   x = 12,102.52/111.43
6. Step 6: Final answer
   x = 108.61