Finding the Fourth Proportional to 105.31, 158.04 and 78.18

Step by Step Solution

1. Step 1: Write the proportion equation
   105.31 : 158.04 = 78.18 : x
2. Step 2: Convert to fraction form
   105.31/158.04 = 78.18/x
3. Step 3: Cross multiply
   105.31x = 158.04 × 78.18
4. Step 4: Simplify right side
   105.31x = 12,355.57
5. Step 5: Solve for x
   x = 12,355.57/105.31
6. Step 6: Final answer
   x = 117.33