Finding the Fourth Proportional to 2,178.23, 3,265.92 and 861.57

Step by Step Solution

1. Step 1: Write the proportion equation
   2,178.23 : 3,265.92 = 861.57 : x
2. Step 2: Convert to fraction form
   2,178.23/3,265.92 = 861.57/x
3. Step 3: Cross multiply
   2,178.23x = 3,265.92 × 861.57
4. Step 4: Simplify right side
   2,178.23x = 2,813,818.69
5. Step 5: Solve for x
   x = 2,813,818.69/2,178.23
6. Step 6: Final answer
   x = 1,291.79