Finding the Fourth Proportional to 1,311.57, 1,809.98 and 722.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,311.57 : 1,809.98 = 722.15 : x
2. Step 2: Convert to fraction form
   1,311.57/1,809.98 = 722.15/x
3. Step 3: Cross multiply
   1,311.57x = 1,809.98 × 722.15
4. Step 4: Simplify right side
   1,311.57x = 1,307,073.89
5. Step 5: Solve for x
   x = 1,307,073.89/1,311.57
6. Step 6: Final answer
   x = 996.57