Finding the Fourth Proportional to 2,101.74, 3,151.86 and 640.50

Step by Step Solution

1. Step 1: Write the proportion equation
   2,101.74 : 3,151.86 = 640.50 : x
2. Step 2: Convert to fraction form
   2,101.74/3,151.86 = 640.50/x
3. Step 3: Cross multiply
   2,101.74x = 3,151.86 × 640.50
4. Step 4: Simplify right side
   2,101.74x = 2,018,766.33
5. Step 5: Solve for x
   x = 2,018,766.33/2,101.74
6. Step 6: Final answer
   x = 960.52