Finding the Fourth Proportional to 1,680.80, 2,518.89 and 857.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,680.80 : 2,518.89 = 857.34 : x
2. Step 2: Convert to fraction form
   1,680.80/2,518.89 = 857.34/x
3. Step 3: Cross multiply
   1,680.80x = 2,518.89 × 857.34
4. Step 4: Simplify right side
   1,680.80x = 2,159,551.48
5. Step 5: Solve for x
   x = 2,159,551.48/1,680.80
6. Step 6: Final answer
   x = 1,284.83