Finding the Fourth Proportional to 1,123.74, 1,686.27 and 393.48

Step by Step Solution

1. Step 1: Write the proportion equation
   1,123.74 : 1,686.27 = 393.48 : x
2. Step 2: Convert to fraction form
   1,123.74/1,686.27 = 393.48/x
3. Step 3: Cross multiply
   1,123.74x = 1,686.27 × 393.48
4. Step 4: Simplify right side
   1,123.74x = 663,513.52
5. Step 5: Solve for x
   x = 663,513.52/1,123.74
6. Step 6: Final answer
   x = 590.45