Finding the Fourth Proportional to 2,100.74, 3,151.56 and 640.01

Step by Step Solution

1. Step 1: Write the proportion equation
   2,100.74 : 3,151.56 = 640.01 : x
2. Step 2: Convert to fraction form
   2,100.74/3,151.56 = 640.01/x
3. Step 3: Cross multiply
   2,100.74x = 3,151.56 × 640.01
4. Step 4: Simplify right side
   2,100.74x = 2,017,029.92
5. Step 5: Solve for x
   x = 2,017,029.92/2,100.74
6. Step 6: Final answer
   x = 960.15