Finding the Fourth Proportional to 2,100.54, 3,149.90 and 639.35

Step by Step Solution

1. Step 1: Write the proportion equation
   2,100.54 : 3,149.90 = 639.35 : x
2. Step 2: Convert to fraction form
   2,100.54/3,149.90 = 639.35/x
3. Step 3: Cross multiply
   2,100.54x = 3,149.90 × 639.35
4. Step 4: Simplify right side
   2,100.54x = 2,013,888.57
5. Step 5: Solve for x
   x = 2,013,888.57/2,100.54
6. Step 6: Final answer
   x = 958.75