Finding the Fourth Proportional to 2,086.10, 3,128.99 and 853.17

Step by Step Solution

1. Step 1: Write the proportion equation
   2,086.10 : 3,128.99 = 853.17 : x
2. Step 2: Convert to fraction form
   2,086.10/3,128.99 = 853.17/x
3. Step 3: Cross multiply
   2,086.10x = 3,128.99 × 853.17
4. Step 4: Simplify right side
   2,086.10x = 2,669,556.13
5. Step 5: Solve for x
   x = 2,669,556.13/2,086.10
6. Step 6: Final answer
   x = 1,279.69