Finding the Fourth Proportional to 105.84, 158.68 and 78.72

Step by Step Solution

1. Step 1: Write the proportion equation
   105.84 : 158.68 = 78.72 : x
2. Step 2: Convert to fraction form
   105.84/158.68 = 78.72/x
3. Step 3: Cross multiply
   105.84x = 158.68 × 78.72
4. Step 4: Simplify right side
   105.84x = 12,491.29
5. Step 5: Solve for x
   x = 12,491.29/105.84
6. Step 6: Final answer
   x = 118.02