Finding the Fourth Proportional to 1,212.79, 1,673.49 and 688.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,212.79 : 1,673.49 = 688.72 : x
2. Step 2: Convert to fraction form
   1,212.79/1,673.49 = 688.72/x
3. Step 3: Cross multiply
   1,212.79x = 1,673.49 × 688.72
4. Step 4: Simplify right side
   1,212.79x = 1,152,566.03
5. Step 5: Solve for x
   x = 1,152,566.03/1,212.79
6. Step 6: Final answer
   x = 950.34