Finding the Fourth Proportional to 1,139.72, 1,707.56 and 408.83

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.72 : 1,707.56 = 408.83 : x
2. Step 2: Convert to fraction form
   1,139.72/1,707.56 = 408.83/x
3. Step 3: Cross multiply
   1,139.72x = 1,707.56 × 408.83
4. Step 4: Simplify right side
   1,139.72x = 698,099.71
5. Step 5: Solve for x
   x = 698,099.71/1,139.72
6. Step 6: Final answer
   x = 612.52