Finding the Fourth Proportional to 2,100.24, 3,150.81 and 639.51

Step by Step Solution

1. Step 1: Write the proportion equation
   2,100.24 : 3,150.81 = 639.51 : x
2. Step 2: Convert to fraction form
   2,100.24/3,150.81 = 639.51/x
3. Step 3: Cross multiply
   2,100.24x = 3,150.81 × 639.51
4. Step 4: Simplify right side
   2,100.24x = 2,014,974.50
5. Step 5: Solve for x
   x = 2,014,974.50/2,100.24
6. Step 6: Final answer
   x = 959.40