Finding the Fourth Proportional to 3,128.78, 4,691.45 and 1,047.69

Step by Step Solution

1. Step 1: Write the proportion equation
   3,128.78 : 4,691.45 = 1,047.69 : x
2. Step 2: Convert to fraction form
   3,128.78/4,691.45 = 1,047.69/x
3. Step 3: Cross multiply
   3,128.78x = 4,691.45 × 1,047.69
4. Step 4: Simplify right side
   3,128.78x = 4,915,185.25
5. Step 5: Solve for x
   x = 4,915,185.25/3,128.78
6. Step 6: Final answer
   x = 1,570.96