Finding the Fourth Proportional to 1,411.20, 1,947.42 and 813.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,411.20 : 1,947.42 = 813.80 : x
2. Step 2: Convert to fraction form
   1,411.20/1,947.42 = 813.80/x
3. Step 3: Cross multiply
   1,411.20x = 1,947.42 × 813.80
4. Step 4: Simplify right side
   1,411.20x = 1,584,810.40
5. Step 5: Solve for x
   x = 1,584,810.40/1,411.20
6. Step 6: Final answer
   x = 1,123.02