Finding the Fourth Proportional to 105.71, 145.37 and 91.91

Step by Step Solution

1. Step 1: Write the proportion equation
   105.71 : 145.37 = 91.91 : x
2. Step 2: Convert to fraction form
   105.71/145.37 = 91.91/x
3. Step 3: Cross multiply
   105.71x = 145.37 × 91.91
4. Step 4: Simplify right side
   105.71x = 13,359.77
5. Step 5: Solve for x
   x = 13,359.77/105.71
6. Step 6: Final answer
   x = 126.39