Finding the Fourth Proportional to 2,640.20, 3,957.53 and 1,081.25

Step by Step Solution

1. Step 1: Write the proportion equation
   2,640.20 : 3,957.53 = 1,081.25 : x
2. Step 2: Convert to fraction form
   2,640.20/3,957.53 = 1,081.25/x
3. Step 3: Cross multiply
   2,640.20x = 3,957.53 × 1,081.25
4. Step 4: Simplify right side
   2,640.20x = 4,279,068.96
5. Step 5: Solve for x
   x = 4,279,068.96/2,640.20
6. Step 6: Final answer
   x = 1,620.74