Finding the Fourth Proportional to 1,139.14, 1,571.38 and 690.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.14 : 1,571.38 = 690.72 : x
2. Step 2: Convert to fraction form
   1,139.14/1,571.38 = 690.72/x
3. Step 3: Cross multiply
   1,139.14x = 1,571.38 × 690.72
4. Step 4: Simplify right side
   1,139.14x = 1,085,383.59
5. Step 5: Solve for x
   x = 1,085,383.59/1,139.14
6. Step 6: Final answer
   x = 952.81