Finding the Fourth Proportional to 1,123.78, 1,685.37 and 343.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,123.78 : 1,685.37 = 343.57 : x
2. Step 2: Convert to fraction form
   1,123.78/1,685.37 = 343.57/x
3. Step 3: Cross multiply
   1,123.78x = 1,685.37 × 343.57
4. Step 4: Simplify right side
   1,123.78x = 579,042.57
5. Step 5: Solve for x
   x = 579,042.57/1,123.78
6. Step 6: Final answer
   x = 515.26