Finding the Fourth Proportional to 2,100.16, 3,149.28 and 639.28

Step by Step Solution

1. Step 1: Write the proportion equation
   2,100.16 : 3,149.28 = 639.28 : x
2. Step 2: Convert to fraction form
   2,100.16/3,149.28 = 639.28/x
3. Step 3: Cross multiply
   2,100.16x = 3,149.28 × 639.28
4. Step 4: Simplify right side
   2,100.16x = 2,013,271.72
5. Step 5: Solve for x
   x = 2,013,271.72/2,100.16
6. Step 6: Final answer
   x = 958.63