Finding the Fourth Proportional to 1,128.10, 1,556.76 and 630.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.10 : 1,556.76 = 630.76 : x
2. Step 2: Convert to fraction form
   1,128.10/1,556.76 = 630.76/x
3. Step 3: Cross multiply
   1,128.10x = 1,556.76 × 630.76
4. Step 4: Simplify right side
   1,128.10x = 981,941.94
5. Step 5: Solve for x
   x = 981,941.94/1,128.10
6. Step 6: Final answer
   x = 870.44