Finding the Fourth Proportional to 2,104.76, 3,156.96 and 643.98

Step by Step Solution

1. Step 1: Write the proportion equation
   2,104.76 : 3,156.96 = 643.98 : x
2. Step 2: Convert to fraction form
   2,104.76/3,156.96 = 643.98/x
3. Step 3: Cross multiply
   2,104.76x = 3,156.96 × 643.98
4. Step 4: Simplify right side
   2,104.76x = 2,033,019.10
5. Step 5: Solve for x
   x = 2,033,019.10/2,104.76
6. Step 6: Final answer
   x = 965.91