Finding the Fourth Proportional to 2,591.80, 3,888.42 and 860.56

Step by Step Solution

1. Step 1: Write the proportion equation
   2,591.80 : 3,888.42 = 860.56 : x
2. Step 2: Convert to fraction form
   2,591.80/3,888.42 = 860.56/x
3. Step 3: Cross multiply
   2,591.80x = 3,888.42 × 860.56
4. Step 4: Simplify right side
   2,591.80x = 3,346,218.72
5. Step 5: Solve for x
   x = 3,346,218.72/2,591.80
6. Step 6: Final answer
   x = 1,291.08