Finding the Fourth Proportional to 1,212.57, 1,673.43 and 688.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,212.57 : 1,673.43 = 688.71 : x
2. Step 2: Convert to fraction form
   1,212.57/1,673.43 = 688.71/x
3. Step 3: Cross multiply
   1,212.57x = 1,673.43 × 688.71
4. Step 4: Simplify right side
   1,212.57x = 1,152,507.98
5. Step 5: Solve for x
   x = 1,152,507.98/1,212.57
6. Step 6: Final answer
   x = 950.47