Finding the Fourth Proportional to 1,139.11, 1,570.52 and 765.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.11 : 1,570.52 = 765.50 : x
2. Step 2: Convert to fraction form
   1,139.11/1,570.52 = 765.50/x
3. Step 3: Cross multiply
   1,139.11x = 1,570.52 × 765.50
4. Step 4: Simplify right side
   1,139.11x = 1,202,227.12
5. Step 5: Solve for x
   x = 1,202,227.12/1,139.11
6. Step 6: Final answer
   x = 1,055.41