Finding the Fourth Proportional to 2,091.92, 3,138.57 and 859.91

Step by Step Solution

1. Step 1: Write the proportion equation
   2,091.92 : 3,138.57 = 859.91 : x
2. Step 2: Convert to fraction form
   2,091.92/3,138.57 = 859.91/x
3. Step 3: Cross multiply
   2,091.92x = 3,138.57 × 859.91
4. Step 4: Simplify right side
   2,091.92x = 2,698,883.43
5. Step 5: Solve for x
   x = 2,698,883.43/2,091.92
6. Step 6: Final answer
   x = 1,290.15