Finding the Fourth Proportional to 111.50, 153.79 and 78.76

Step by Step Solution

1. Step 1: Write the proportion equation
   111.50 : 153.79 = 78.76 : x
2. Step 2: Convert to fraction form
   111.50/153.79 = 78.76/x
3. Step 3: Cross multiply
   111.50x = 153.79 × 78.76
4. Step 4: Simplify right side
   111.50x = 12,111.92
5. Step 5: Solve for x
   x = 12,111.92/111.50
6. Step 6: Final answer
   x = 108.63