Finding the Fourth Proportional to 2,086.35, 3,128.10 and 853.39

Step by Step Solution

1. Step 1: Write the proportion equation
   2,086.35 : 3,128.10 = 853.39 : x
2. Step 2: Convert to fraction form
   2,086.35/3,128.10 = 853.39/x
3. Step 3: Cross multiply
   2,086.35x = 3,128.10 × 853.39
4. Step 4: Simplify right side
   2,086.35x = 2,669,489.26
5. Step 5: Solve for x
   x = 2,669,489.26/2,086.35
6. Step 6: Final answer
   x = 1,279.50