Finding the Fourth Proportional to 1,856.91, 2,785.59 and 686.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,856.91 : 2,785.59 = 686.71 : x
2. Step 2: Convert to fraction form
   1,856.91/2,785.59 = 686.71/x
3. Step 3: Cross multiply
   1,856.91x = 2,785.59 × 686.71
4. Step 4: Simplify right side
   1,856.91x = 1,912,895.99
5. Step 5: Solve for x
   x = 1,912,895.99/1,856.91
6. Step 6: Final answer
   x = 1,030.15