Finding the Fourth Proportional to 2,826.72, 4,239.75 and 878.40

Step by Step Solution

1. Step 1: Write the proportion equation
   2,826.72 : 4,239.75 = 878.40 : x
2. Step 2: Convert to fraction form
   2,826.72/4,239.75 = 878.40/x
3. Step 3: Cross multiply
   2,826.72x = 4,239.75 × 878.40
4. Step 4: Simplify right side
   2,826.72x = 3,724,196.40
5. Step 5: Solve for x
   x = 3,724,196.40/2,826.72
6. Step 6: Final answer
   x = 1,317.50