Finding the Fourth Proportional to 1,856.50, 2,783.89 and 686.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,856.50 : 2,783.89 = 686.21 : x
2. Step 2: Convert to fraction form
   1,856.50/2,783.89 = 686.21/x
3. Step 3: Cross multiply
   1,856.50x = 2,783.89 × 686.21
4. Step 4: Simplify right side
   1,856.50x = 1,910,333.16
5. Step 5: Solve for x
   x = 1,910,333.16/1,856.50
6. Step 6: Final answer
   x = 1,029.00