Finding the Fourth Proportional to 1,128.65, 1,557.61 and 631.27

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.65 : 1,557.61 = 631.27 : x
2. Step 2: Convert to fraction form
   1,128.65/1,557.61 = 631.27/x
3. Step 3: Cross multiply
   1,128.65x = 1,557.61 × 631.27
4. Step 4: Simplify right side
   1,128.65x = 983,272.83
5. Step 5: Solve for x
   x = 983,272.83/1,128.65
6. Step 6: Final answer
   x = 871.20