Finding the Fourth Proportional to 86.82, 129.69 and 57.69

Step by Step Solution

1. Step 1: Write the proportion equation
   86.82 : 129.69 = 57.69 : x
2. Step 2: Convert to fraction form
   86.82/129.69 = 57.69/x
3. Step 3: Cross multiply
   86.82x = 129.69 × 57.69
4. Step 4: Simplify right side
   86.82x = 7,481.82
5. Step 5: Solve for x
   x = 7,481.82/86.82
6. Step 6: Final answer
   x = 86.18