Finding the Fourth Proportional to 1,139.50, 1,572.15 and 697.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.50 : 1,572.15 = 697.18 : x
2. Step 2: Convert to fraction form
   1,139.50/1,572.15 = 697.18/x
3. Step 3: Cross multiply
   1,139.50x = 1,572.15 × 697.18
4. Step 4: Simplify right side
   1,139.50x = 1,096,071.54
5. Step 5: Solve for x
   x = 1,096,071.54/1,139.50
6. Step 6: Final answer
   x = 961.89