Finding the Fourth Proportional to 105.72, 145.94 and 82.40

Step by Step Solution

1. Step 1: Write the proportion equation
   105.72 : 145.94 = 82.40 : x
2. Step 2: Convert to fraction form
   105.72/145.94 = 82.40/x
3. Step 3: Cross multiply
   105.72x = 145.94 × 82.40
4. Step 4: Simplify right side
   105.72x = 12,024.31
5. Step 5: Solve for x
   x = 12,024.31/105.72
6. Step 6: Final answer
   x = 113.74