Finding the Fourth Proportional to 105.31, 158.16 and 82.40

Step by Step Solution

1. Step 1: Write the proportion equation
   105.31 : 158.16 = 82.40 : x
2. Step 2: Convert to fraction form
   105.31/158.16 = 82.40/x
3. Step 3: Cross multiply
   105.31x = 158.16 × 82.40
4. Step 4: Simplify right side
   105.31x = 13,032.38
5. Step 5: Solve for x
   x = 13,032.38/105.31
6. Step 6: Final answer
   x = 123.75