Finding the Fourth Proportional to 1,320.25, 1,821.98 and 855.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,320.25 : 1,821.98 = 855.31 : x
2. Step 2: Convert to fraction form
   1,320.25/1,821.98 = 855.31/x
3. Step 3: Cross multiply
   1,320.25x = 1,821.98 × 855.31
4. Step 4: Simplify right side
   1,320.25x = 1,558,357.71
5. Step 5: Solve for x
   x = 1,558,357.71/1,320.25
6. Step 6: Final answer
   x = 1,180.35