Finding the Fourth Proportional to 2,101.57, 3,152.69 and 640.38

Step by Step Solution

1. Step 1: Write the proportion equation
   2,101.57 : 3,152.69 = 640.38 : x
2. Step 2: Convert to fraction form
   2,101.57/3,152.69 = 640.38/x
3. Step 3: Cross multiply
   2,101.57x = 3,152.69 × 640.38
4. Step 4: Simplify right side
   2,101.57x = 2,018,919.62
5. Step 5: Solve for x
   x = 2,018,919.62/2,101.57
6. Step 6: Final answer
   x = 960.67