Finding the Fourth Proportional to 1,212.66, 1,673.50 and 688.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,212.66 : 1,673.50 = 688.72 : x
2. Step 2: Convert to fraction form
   1,212.66/1,673.50 = 688.72/x
3. Step 3: Cross multiply
   1,212.66x = 1,673.50 × 688.72
4. Step 4: Simplify right side
   1,212.66x = 1,152,572.92
5. Step 5: Solve for x
   x = 1,152,572.92/1,212.66
6. Step 6: Final answer
   x = 950.45