Finding the Fourth Proportional to 1,211.52, 1,672.02 and 687.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,211.52 : 1,672.02 = 687.72 : x
2. Step 2: Convert to fraction form
   1,211.52/1,672.02 = 687.72/x
3. Step 3: Cross multiply
   1,211.52x = 1,672.02 × 687.72
4. Step 4: Simplify right side
   1,211.52x = 1,149,881.59
5. Step 5: Solve for x
   x = 1,149,881.59/1,211.52
6. Step 6: Final answer
   x = 949.12