Finding the Fourth Proportional to 105.42, 158.13 and 91.86

Step by Step Solution

1. Step 1: Write the proportion equation
   105.42 : 158.13 = 91.86 : x
2. Step 2: Convert to fraction form
   105.42/158.13 = 91.86/x
3. Step 3: Cross multiply
   105.42x = 158.13 × 91.86
4. Step 4: Simplify right side
   105.42x = 14,525.82
5. Step 5: Solve for x
   x = 14,525.82/105.42
6. Step 6: Final answer
   x = 137.79