Finding the Fourth Proportional to 105.20, 144.96 and 86.72

Step by Step Solution

1. Step 1: Write the proportion equation
   105.20 : 144.96 = 86.72 : x
2. Step 2: Convert to fraction form
   105.20/144.96 = 86.72/x
3. Step 3: Cross multiply
   105.20x = 144.96 × 86.72
4. Step 4: Simplify right side
   105.20x = 12,570.93
5. Step 5: Solve for x
   x = 12,570.93/105.20
6. Step 6: Final answer
   x = 119.50