Finding the Fourth Proportional to 105.78, 158.49 and 78.27

Step by Step Solution

1. Step 1: Write the proportion equation
   105.78 : 158.49 = 78.27 : x
2. Step 2: Convert to fraction form
   105.78/158.49 = 78.27/x
3. Step 3: Cross multiply
   105.78x = 158.49 × 78.27
4. Step 4: Simplify right side
   105.78x = 12,405.01
5. Step 5: Solve for x
   x = 12,405.01/105.78
6. Step 6: Final answer
   x = 117.27