Finding the Fourth Proportional to 1,212.39, 1,672.72 and 688.32

Step by Step Solution

1. Step 1: Write the proportion equation
   1,212.39 : 1,672.72 = 688.32 : x
2. Step 2: Convert to fraction form
   1,212.39/1,672.72 = 688.32/x
3. Step 3: Cross multiply
   1,212.39x = 1,672.72 × 688.32
4. Step 4: Simplify right side
   1,212.39x = 1,151,364.91
5. Step 5: Solve for x
   x = 1,151,364.91/1,212.39
6. Step 6: Final answer
   x = 949.67