Finding the Fourth Proportional to 1,247.69, 1,721.83 and 688.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,247.69 : 1,721.83 = 688.18 : x
2. Step 2: Convert to fraction form
   1,247.69/1,721.83 = 688.18/x
3. Step 3: Cross multiply
   1,247.69x = 1,721.83 × 688.18
4. Step 4: Simplify right side
   1,247.69x = 1,184,928.54
5. Step 5: Solve for x
   x = 1,184,928.54/1,247.69
6. Step 6: Final answer
   x = 949.70