Finding the Fourth Proportional to 86.37, 128.89 and 77.73

Step by Step Solution

1. Step 1: Write the proportion equation
   86.37 : 128.89 = 77.73 : x
2. Step 2: Convert to fraction form
   86.37/128.89 = 77.73/x
3. Step 3: Cross multiply
   86.37x = 128.89 × 77.73
4. Step 4: Simplify right side
   86.37x = 10,018.23
5. Step 5: Solve for x
   x = 10,018.23/86.37
6. Step 6: Final answer
   x = 116.00