Finding the Fourth Proportional to 1,392.18, 2,085.03 and 815.46

Step by Step Solution

1. Step 1: Write the proportion equation
   1,392.18 : 2,085.03 = 815.46 : x
2. Step 2: Convert to fraction form
   1,392.18/2,085.03 = 815.46/x
3. Step 3: Cross multiply
   1,392.18x = 2,085.03 × 815.46
4. Step 4: Simplify right side
   1,392.18x = 1,700,258.56
5. Step 5: Solve for x
   x = 1,700,258.56/1,392.18
6. Step 6: Final answer
   x = 1,221.29