Finding the Fourth Proportional to 1,123.48, 1,685.20 and 429.96

Step by Step Solution

1. Step 1: Write the proportion equation
   1,123.48 : 1,685.20 = 429.96 : x
2. Step 2: Convert to fraction form
   1,123.48/1,685.20 = 429.96/x
3. Step 3: Cross multiply
   1,123.48x = 1,685.20 × 429.96
4. Step 4: Simplify right side
   1,123.48x = 724,568.59
5. Step 5: Solve for x
   x = 724,568.59/1,123.48
6. Step 6: Final answer
   x = 644.93