Finding the Fourth Proportional to 1,004.20, 1,386.04 and 611.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,004.20 : 1,386.04 = 611.55 : x
2. Step 2: Convert to fraction form
   1,004.20/1,386.04 = 611.55/x
3. Step 3: Cross multiply
   1,004.20x = 1,386.04 × 611.55
4. Step 4: Simplify right side
   1,004.20x = 847,638.72
5. Step 5: Solve for x
   x = 847,638.72/1,004.20
6. Step 6: Final answer
   x = 844.09