Finding the Fourth Proportional to 2,103.12, 3,155.04 and 642.12

Step by Step Solution

1. Step 1: Write the proportion equation
   2,103.12 : 3,155.04 = 642.12 : x
2. Step 2: Convert to fraction form
   2,103.12/3,155.04 = 642.12/x
3. Step 3: Cross multiply
   2,103.12x = 3,155.04 × 642.12
4. Step 4: Simplify right side
   2,103.12x = 2,025,914.28
5. Step 5: Solve for x
   x = 2,025,914.28/2,103.12
6. Step 6: Final answer
   x = 963.29