Finding the Fourth Proportional to 2,640.21, 3,960.27 and 908.79

Step by Step Solution

1. Step 1: Write the proportion equation
   2,640.21 : 3,960.27 = 908.79 : x
2. Step 2: Convert to fraction form
   2,640.21/3,960.27 = 908.79/x
3. Step 3: Cross multiply
   2,640.21x = 3,960.27 × 908.79
4. Step 4: Simplify right side
   2,640.21x = 3,599,053.77
5. Step 5: Solve for x
   x = 3,599,053.77/2,640.21
6. Step 6: Final answer
   x = 1,363.17