Finding the Fourth Proportional to 1,212.72, 1,673.64 and 688.79

Step by Step Solution

1. Step 1: Write the proportion equation
   1,212.72 : 1,673.64 = 688.79 : x
2. Step 2: Convert to fraction form
   1,212.72/1,673.64 = 688.79/x
3. Step 3: Cross multiply
   1,212.72x = 1,673.64 × 688.79
4. Step 4: Simplify right side
   1,212.72x = 1,152,786.50
5. Step 5: Solve for x
   x = 1,152,786.50/1,212.72
6. Step 6: Final answer
   x = 950.58