Finding the Fourth Proportional to 2,591.56, 3,885.72 and 859.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,591.56 : 3,885.72 = 859.78 : x
2. Step 2: Convert to fraction form
   2,591.56/3,885.72 = 859.78/x
3. Step 3: Cross multiply
   2,591.56x = 3,885.72 × 859.78
4. Step 4: Simplify right side
   2,591.56x = 3,340,864.34
5. Step 5: Solve for x
   x = 3,340,864.34/2,591.56
6. Step 6: Final answer
   x = 1,289.13