Finding the Fourth Proportional to 1,152.30, 1,728.71 and 421.87

Step by Step Solution

1. Step 1: Write the proportion equation
   1,152.30 : 1,728.71 = 421.87 : x
2. Step 2: Convert to fraction form
   1,152.30/1,728.71 = 421.87/x
3. Step 3: Cross multiply
   1,152.30x = 1,728.71 × 421.87
4. Step 4: Simplify right side
   1,152.30x = 729,290.89
5. Step 5: Solve for x
   x = 729,290.89/1,152.30
6. Step 6: Final answer
   x = 632.90