Finding the Fourth Proportional to 1,128.05, 1,556.71 and 630.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.05 : 1,556.71 = 630.71 : x
2. Step 2: Convert to fraction form
   1,128.05/1,556.71 = 630.71/x
3. Step 3: Cross multiply
   1,128.05x = 1,556.71 × 630.71
4. Step 4: Simplify right side
   1,128.05x = 981,823.20
5. Step 5: Solve for x
   x = 981,823.20/1,128.05
6. Step 6: Final answer
   x = 870.38