Finding the Fourth Proportional to 105.72, 158.82 and 91.32

Step by Step Solution

1. Step 1: Write the proportion equation
   105.72 : 158.82 = 91.32 : x
2. Step 2: Convert to fraction form
   105.72/158.82 = 91.32/x
3. Step 3: Cross multiply
   105.72x = 158.82 × 91.32
4. Step 4: Simplify right side
   105.72x = 14,503.44
5. Step 5: Solve for x
   x = 14,503.44/105.72
6. Step 6: Final answer
   x = 137.19