Finding the Fourth Proportional to 105.31, 145.46 and 91.50

Step by Step Solution

1. Step 1: Write the proportion equation
   105.31 : 145.46 = 91.50 : x
2. Step 2: Convert to fraction form
   105.31/145.46 = 91.50/x
3. Step 3: Cross multiply
   105.31x = 145.46 × 91.50
4. Step 4: Simplify right side
   105.31x = 13,309.27
5. Step 5: Solve for x
   x = 13,309.27/105.31
6. Step 6: Final answer
   x = 126.38