Finding the Fourth Proportional to 105.72, 158.34 and 86.52

Step by Step Solution

1. Step 1: Write the proportion equation
   105.72 : 158.34 = 86.52 : x
2. Step 2: Convert to fraction form
   105.72/158.34 = 86.52/x
3. Step 3: Cross multiply
   105.72x = 158.34 × 86.52
4. Step 4: Simplify right side
   105.72x = 13,699.58
5. Step 5: Solve for x
   x = 13,699.58/105.72
6. Step 6: Final answer
   x = 129.58