Finding the Fourth Proportional to 1,321.82, 1,981.31 and 580.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,321.82 : 1,981.31 = 580.78 : x
2. Step 2: Convert to fraction form
   1,321.82/1,981.31 = 580.78/x
3. Step 3: Cross multiply
   1,321.82x = 1,981.31 × 580.78
4. Step 4: Simplify right side
   1,321.82x = 1,150,696.92
5. Step 5: Solve for x
   x = 1,150,696.92/1,321.82
6. Step 6: Final answer
   x = 870.54