Finding the Fourth Proportional to 1,405.17, 1,939.31 and 815.73

Step by Step Solution

1. Step 1: Write the proportion equation
   1,405.17 : 1,939.31 = 815.73 : x
2. Step 2: Convert to fraction form
   1,405.17/1,939.31 = 815.73/x
3. Step 3: Cross multiply
   1,405.17x = 1,939.31 × 815.73
4. Step 4: Simplify right side
   1,405.17x = 1,581,953.35
5. Step 5: Solve for x
   x = 1,581,953.35/1,405.17
6. Step 6: Final answer
   x = 1,125.81