Finding the Fourth Proportional to 2,103.58, 3,155.68 and 642.55

Step by Step Solution

1. Step 1: Write the proportion equation
   2,103.58 : 3,155.68 = 642.55 : x
2. Step 2: Convert to fraction form
   2,103.58/3,155.68 = 642.55/x
3. Step 3: Cross multiply
   2,103.58x = 3,155.68 × 642.55
4. Step 4: Simplify right side
   2,103.58x = 2,027,665.44
5. Step 5: Solve for x
   x = 2,027,665.44/2,103.58
6. Step 6: Final answer
   x = 963.91