Finding the Fourth Proportional to 1,123.92, 1,685.34 and 393.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,123.92 : 1,685.34 = 393.30 : x
2. Step 2: Convert to fraction form
   1,123.92/1,685.34 = 393.30/x
3. Step 3: Cross multiply
   1,123.92x = 1,685.34 × 393.30
4. Step 4: Simplify right side
   1,123.92x = 662,844.22
5. Step 5: Solve for x
   x = 662,844.22/1,123.92
6. Step 6: Final answer
   x = 589.76