Finding the Fourth Proportional to 2,100.74, 3,150.36 and 639.50

Step by Step Solution

1. Step 1: Write the proportion equation
   2,100.74 : 3,150.36 = 639.50 : x
2. Step 2: Convert to fraction form
   2,100.74/3,150.36 = 639.50/x
3. Step 3: Cross multiply
   2,100.74x = 3,150.36 × 639.50
4. Step 4: Simplify right side
   2,100.74x = 2,014,639.47
5. Step 5: Solve for x
   x = 2,014,639.47/2,100.74
6. Step 6: Final answer
   x = 959.02