Finding the Fourth Proportional to 1,223.62, 1,688.98 and 782.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,223.62 : 1,688.98 = 782.71 : x
2. Step 2: Convert to fraction form
   1,223.62/1,688.98 = 782.71/x
3. Step 3: Cross multiply
   1,223.62x = 1,688.98 × 782.71
4. Step 4: Simplify right side
   1,223.62x = 1,321,981.54
5. Step 5: Solve for x
   x = 1,321,981.54/1,223.62
6. Step 6: Final answer
   x = 1,080.39