Finding the Fourth Proportional to 105.58, 158.15 and 78.09

Step by Step Solution

1. Step 1: Write the proportion equation
   105.58 : 158.15 = 78.09 : x
2. Step 2: Convert to fraction form
   105.58/158.15 = 78.09/x
3. Step 3: Cross multiply
   105.58x = 158.15 × 78.09
4. Step 4: Simplify right side
   105.58x = 12,348.75
5. Step 5: Solve for x
   x = 12,348.75/105.58
6. Step 6: Final answer
   x = 116.96