Finding the Fourth Proportional to 1,128.61, 1,557.32 and 631.16

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.61 : 1,557.32 = 631.16 : x
2. Step 2: Convert to fraction form
   1,128.61/1,557.32 = 631.16/x
3. Step 3: Cross multiply
   1,128.61x = 1,557.32 × 631.16
4. Step 4: Simplify right side
   1,128.61x = 982,907.15
5. Step 5: Solve for x
   x = 982,907.15/1,128.61
6. Step 6: Final answer
   x = 870.90