Finding the Fourth Proportional to 1,139.68, 1,572.79 and 697.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.68 : 1,572.79 = 697.57 : x
2. Step 2: Convert to fraction form
   1,139.68/1,572.79 = 697.57/x
3. Step 3: Cross multiply
   1,139.68x = 1,572.79 × 697.57
4. Step 4: Simplify right side
   1,139.68x = 1,097,131.12
5. Step 5: Solve for x
   x = 1,097,131.12/1,139.68
6. Step 6: Final answer
   x = 962.67