Finding the Fourth Proportional to 2,200.10, 3,299.63 and 639.69

Step by Step Solution

1. Step 1: Write the proportion equation
   2,200.10 : 3,299.63 = 639.69 : x
2. Step 2: Convert to fraction form
   2,200.10/3,299.63 = 639.69/x
3. Step 3: Cross multiply
   2,200.10x = 3,299.63 × 639.69
4. Step 4: Simplify right side
   2,200.10x = 2,110,740.31
5. Step 5: Solve for x
   x = 2,110,740.31/2,200.10
6. Step 6: Final answer
   x = 959.38