Finding the Fourth Proportional to 1,139.30, 1,572.20 and 697.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.30 : 1,572.20 = 697.10 : x
2. Step 2: Convert to fraction form
   1,139.30/1,572.20 = 697.10/x
3. Step 3: Cross multiply
   1,139.30x = 1,572.20 × 697.10
4. Step 4: Simplify right side
   1,139.30x = 1,095,980.62
5. Step 5: Solve for x
   x = 1,095,980.62/1,139.30
6. Step 6: Final answer
   x = 961.98