Finding the Fourth Proportional to 1,223.69, 1,688.42 and 699.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,223.69 : 1,688.42 = 699.71 : x
2. Step 2: Convert to fraction form
   1,223.69/1,688.42 = 699.71/x
3. Step 3: Cross multiply
   1,223.69x = 1,688.42 × 699.71
4. Step 4: Simplify right side
   1,223.69x = 1,181,400.86
5. Step 5: Solve for x
   x = 1,181,400.86/1,223.69
6. Step 6: Final answer
   x = 965.44