Finding the Fourth Proportional to 1,123.16, 1,685.01 and 392.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,123.16 : 1,685.01 = 392.81 : x
2. Step 2: Convert to fraction form
   1,123.16/1,685.01 = 392.81/x
3. Step 3: Cross multiply
   1,123.16x = 1,685.01 × 392.81
4. Step 4: Simplify right side
   1,123.16x = 661,888.78
5. Step 5: Solve for x
   x = 661,888.78/1,123.16
6. Step 6: Final answer
   x = 589.31