Finding the Fourth Proportional to 105.86, 158.94 and 81.98

Step by Step Solution

1. Step 1: Write the proportion equation
   105.86 : 158.94 = 81.98 : x
2. Step 2: Convert to fraction form
   105.86/158.94 = 81.98/x
3. Step 3: Cross multiply
   105.86x = 158.94 × 81.98
4. Step 4: Simplify right side
   105.86x = 13,029.90
5. Step 5: Solve for x
   x = 13,029.90/105.86
6. Step 6: Final answer
   x = 123.09