Finding the Fourth Proportional to 1,405.09, 1,938.71 and 815.28

Step by Step Solution

1. Step 1: Write the proportion equation
   1,405.09 : 1,938.71 = 815.28 : x
2. Step 2: Convert to fraction form
   1,405.09/1,938.71 = 815.28/x
3. Step 3: Cross multiply
   1,405.09x = 1,938.71 × 815.28
4. Step 4: Simplify right side
   1,405.09x = 1,580,590.47
5. Step 5: Solve for x
   x = 1,580,590.47/1,405.09
6. Step 6: Final answer
   x = 1,124.91