Finding the Fourth Proportional to 1,478.72, 2,040.61 and 815.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,478.72 : 2,040.61 = 815.57 : x
2. Step 2: Convert to fraction form
   1,478.72/2,040.61 = 815.57/x
3. Step 3: Cross multiply
   1,478.72x = 2,040.61 × 815.57
4. Step 4: Simplify right side
   1,478.72x = 1,664,260.30
5. Step 5: Solve for x
   x = 1,664,260.30/1,478.72
6. Step 6: Final answer
   x = 1,125.47