Finding the Fourth Proportional to 1,139.57, 1,571.78 and 697.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.57 : 1,571.78 = 697.71 : x
2. Step 2: Convert to fraction form
   1,139.57/1,571.78 = 697.71/x
3. Step 3: Cross multiply
   1,139.57x = 1,571.78 × 697.71
4. Step 4: Simplify right side
   1,139.57x = 1,096,648.37
5. Step 5: Solve for x
   x = 1,096,648.37/1,139.57
6. Step 6: Final answer
   x = 962.34