Finding the Fourth Proportional to 105.76, 158.72 and 91.68

Step by Step Solution

1. Step 1: Write the proportion equation
   105.76 : 158.72 = 91.68 : x
2. Step 2: Convert to fraction form
   105.76/158.72 = 91.68/x
3. Step 3: Cross multiply
   105.76x = 158.72 × 91.68
4. Step 4: Simplify right side
   105.76x = 14,551.45
5. Step 5: Solve for x
   x = 14,551.45/105.76
6. Step 6: Final answer
   x = 137.59