Finding the Fourth Proportional to 105.68, 158.58 and 78.76

Step by Step Solution

1. Step 1: Write the proportion equation
   105.68 : 158.58 = 78.76 : x
2. Step 2: Convert to fraction form
   105.68/158.58 = 78.76/x
3. Step 3: Cross multiply
   105.68x = 158.58 × 78.76
4. Step 4: Simplify right side
   105.68x = 12,489.76
5. Step 5: Solve for x
   x = 12,489.76/105.68
6. Step 6: Final answer
   x = 118.18