Finding the Fourth Proportional to 1,128.69, 1,556.91 and 939.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.69 : 1,556.91 = 939.15 : x
2. Step 2: Convert to fraction form
   1,128.69/1,556.91 = 939.15/x
3. Step 3: Cross multiply
   1,128.69x = 1,556.91 × 939.15
4. Step 4: Simplify right side
   1,128.69x = 1,462,172.03
5. Step 5: Solve for x
   x = 1,462,172.03/1,128.69
6. Step 6: Final answer
   x = 1,295.46