Finding the Fourth Proportional to 2,101.34, 3,151.58 and 640.20

Step by Step Solution

1. Step 1: Write the proportion equation
   2,101.34 : 3,151.58 = 640.20 : x
2. Step 2: Convert to fraction form
   2,101.34/3,151.58 = 640.20/x
3. Step 3: Cross multiply
   2,101.34x = 3,151.58 × 640.20
4. Step 4: Simplify right side
   2,101.34x = 2,017,641.52
5. Step 5: Solve for x
   x = 2,017,641.52/2,101.34
6. Step 6: Final answer
   x = 960.17