Finding the Fourth Proportional to 1,722.80, 2,582.88 and 857.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,722.80 : 2,582.88 = 857.72 : x
2. Step 2: Convert to fraction form
   1,722.80/2,582.88 = 857.72/x
3. Step 3: Cross multiply
   1,722.80x = 2,582.88 × 857.72
4. Step 4: Simplify right side
   1,722.80x = 2,215,387.83
5. Step 5: Solve for x
   x = 2,215,387.83/1,722.80
6. Step 6: Final answer
   x = 1,285.92