Finding the Fourth Proportional to 2,085.40, 3,128.46 and 853.48

Step by Step Solution

1. Step 1: Write the proportion equation
   2,085.40 : 3,128.46 = 853.48 : x
2. Step 2: Convert to fraction form
   2,085.40/3,128.46 = 853.48/x
3. Step 3: Cross multiply
   2,085.40x = 3,128.46 × 853.48
4. Step 4: Simplify right side
   2,085.40x = 2,670,078.04
5. Step 5: Solve for x
   x = 2,670,078.04/2,085.40
6. Step 6: Final answer
   x = 1,280.37