Finding the Fourth Proportional to 2,128.05, 3,186.15 and 1,085.80

Step by Step Solution

1. Step 1: Write the proportion equation
   2,128.05 : 3,186.15 = 1,085.80 : x
2. Step 2: Convert to fraction form
   2,128.05/3,186.15 = 1,085.80/x
3. Step 3: Cross multiply
   2,128.05x = 3,186.15 × 1,085.80
4. Step 4: Simplify right side
   2,128.05x = 3,459,521.67
5. Step 5: Solve for x
   x = 3,459,521.67/2,128.05
6. Step 6: Final answer
   x = 1,625.68