Finding the Fourth Proportional to 1,128.72, 1,557.54 and 631.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.72 : 1,557.54 = 631.43 : x
2. Step 2: Convert to fraction form
   1,128.72/1,557.54 = 631.43/x
3. Step 3: Cross multiply
   1,128.72x = 1,557.54 × 631.43
4. Step 4: Simplify right side
   1,128.72x = 983,477.48
5. Step 5: Solve for x
   x = 983,477.48/1,128.72
6. Step 6: Final answer
   x = 871.32