Finding the Fourth Proportional to 1,128.79, 1,557.52 and 631.38

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.79 : 1,557.52 = 631.38 : x
2. Step 2: Convert to fraction form
   1,128.79/1,557.52 = 631.38/x
3. Step 3: Cross multiply
   1,128.79x = 1,557.52 × 631.38
4. Step 4: Simplify right side
   1,128.79x = 983,386.98
5. Step 5: Solve for x
   x = 983,386.98/1,128.79
6. Step 6: Final answer
   x = 871.19