Finding the Fourth Proportional to 2,105.61, 3,158.79 and 872.36

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.61 : 3,158.79 = 872.36 : x
2. Step 2: Convert to fraction form
   2,105.61/3,158.79 = 872.36/x
3. Step 3: Cross multiply
   2,105.61x = 3,158.79 × 872.36
4. Step 4: Simplify right side
   2,105.61x = 2,755,602.04
5. Step 5: Solve for x
   x = 2,755,602.04/2,105.61
6. Step 6: Final answer
   x = 1,308.70