Finding the Fourth Proportional to 1,385.51, 1,911.20 and 825.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,385.51 : 1,911.20 = 825.80 : x
2. Step 2: Convert to fraction form
   1,385.51/1,911.20 = 825.80/x
3. Step 3: Cross multiply
   1,385.51x = 1,911.20 × 825.80
4. Step 4: Simplify right side
   1,385.51x = 1,578,255.28
5. Step 5: Solve for x
   x = 1,578,255.28/1,385.51
6. Step 6: Final answer
   x = 1,139.12