Finding the Fourth Proportional to 2,100.67, 3,151.10 and 639.83

Step by Step Solution

1. Step 1: Write the proportion equation
   2,100.67 : 3,151.10 = 639.83 : x
2. Step 2: Convert to fraction form
   2,100.67/3,151.10 = 639.83/x
3. Step 3: Cross multiply
   2,100.67x = 3,151.10 × 639.83
4. Step 4: Simplify right side
   2,100.67x = 2,016,177.79
5. Step 5: Solve for x
   x = 2,016,177.79/2,100.67
6. Step 6: Final answer
   x = 959.78