Finding the Fourth Proportional to 105.54, 158.31 and 78.54

Step by Step Solution

1. Step 1: Write the proportion equation
   105.54 : 158.31 = 78.54 : x
2. Step 2: Convert to fraction form
   105.54/158.31 = 78.54/x
3. Step 3: Cross multiply
   105.54x = 158.31 × 78.54
4. Step 4: Simplify right side
   105.54x = 12,433.67
5. Step 5: Solve for x
   x = 12,433.67/105.54
6. Step 6: Final answer
   x = 117.81