Finding the Fourth Proportional to 1,123.05, 1,685.07 and 393.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,123.05 : 1,685.07 = 393.15 : x
2. Step 2: Convert to fraction form
   1,123.05/1,685.07 = 393.15/x
3. Step 3: Cross multiply
   1,123.05x = 1,685.07 × 393.15
4. Step 4: Simplify right side
   1,123.05x = 662,485.27
5. Step 5: Solve for x
   x = 662,485.27/1,123.05
6. Step 6: Final answer
   x = 589.90