Finding the Fourth Proportional to 107.82, 161.69 and 77.31

Step by Step Solution

1. Step 1: Write the proportion equation
   107.82 : 161.69 = 77.31 : x
2. Step 2: Convert to fraction form
   107.82/161.69 = 77.31/x
3. Step 3: Cross multiply
   107.82x = 161.69 × 77.31
4. Step 4: Simplify right side
   107.82x = 12,499.87
5. Step 5: Solve for x
   x = 12,499.87/107.82
6. Step 6: Final answer
   x = 115.93