Finding the Fourth Proportional to 1,128.80, 1,557.82 and 631.47

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.80 : 1,557.82 = 631.47 : x
2. Step 2: Convert to fraction form
   1,128.80/1,557.82 = 631.47/x
3. Step 3: Cross multiply
   1,128.80x = 1,557.82 × 631.47
4. Step 4: Simplify right side
   1,128.80x = 983,715.29
5. Step 5: Solve for x
   x = 983,715.29/1,128.80
6. Step 6: Final answer
   x = 871.47