Finding the Fourth Proportional to 2,103.97, 3,155.72 and 643.13

Step by Step Solution

1. Step 1: Write the proportion equation
   2,103.97 : 3,155.72 = 643.13 : x
2. Step 2: Convert to fraction form
   2,103.97/3,155.72 = 643.13/x
3. Step 3: Cross multiply
   2,103.97x = 3,155.72 × 643.13
4. Step 4: Simplify right side
   2,103.97x = 2,029,538.20
5. Step 5: Solve for x
   x = 2,029,538.20/2,103.97
6. Step 6: Final answer
   x = 964.62