Finding the Fourth Proportional to 1,040.55, 1,561.05 and 391.29

Step by Step Solution

1. Step 1: Write the proportion equation
   1,040.55 : 1,561.05 = 391.29 : x
2. Step 2: Convert to fraction form
   1,040.55/1,561.05 = 391.29/x
3. Step 3: Cross multiply
   1,040.55x = 1,561.05 × 391.29
4. Step 4: Simplify right side
   1,040.55x = 610,815.45
5. Step 5: Solve for x
   x = 610,815.45/1,040.55
6. Step 6: Final answer
   x = 587.01