Finding the Fourth Proportional to 1,123.47, 1,684.12 and 429.60

Step by Step Solution

1. Step 1: Write the proportion equation
   1,123.47 : 1,684.12 = 429.60 : x
2. Step 2: Convert to fraction form
   1,123.47/1,684.12 = 429.60/x
3. Step 3: Cross multiply
   1,123.47x = 1,684.12 × 429.60
4. Step 4: Simplify right side
   1,123.47x = 723,502.79
5. Step 5: Solve for x
   x = 723,502.79/1,123.47
6. Step 6: Final answer
   x = 643.99