Finding the Fourth Proportional to 1,298.79, 1,790.98 and 856.13

Step by Step Solution

1. Step 1: Write the proportion equation
   1,298.79 : 1,790.98 = 856.13 : x
2. Step 2: Convert to fraction form
   1,298.79/1,790.98 = 856.13/x
3. Step 3: Cross multiply
   1,298.79x = 1,790.98 × 856.13
4. Step 4: Simplify right side
   1,298.79x = 1,533,300.61
5. Step 5: Solve for x
   x = 1,533,300.61/1,298.79
6. Step 6: Final answer
   x = 1,180.56