Finding the Fourth Proportional to 2,104.56, 3,156.86 and 643.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,104.56 : 3,156.86 = 643.72 : x
2. Step 2: Convert to fraction form
   2,104.56/3,156.86 = 643.72/x
3. Step 3: Cross multiply
   2,104.56x = 3,156.86 × 643.72
4. Step 4: Simplify right side
   2,104.56x = 2,032,133.92
5. Step 5: Solve for x
   x = 2,032,133.92/2,104.56
6. Step 6: Final answer
   x = 965.59