Finding the Fourth Proportional to 1,211.67, 1,672.25 and 687.74

Step by Step Solution

1. Step 1: Write the proportion equation
   1,211.67 : 1,672.25 = 687.74 : x
2. Step 2: Convert to fraction form
   1,211.67/1,672.25 = 687.74/x
3. Step 3: Cross multiply
   1,211.67x = 1,672.25 × 687.74
4. Step 4: Simplify right side
   1,211.67x = 1,150,061.42
5. Step 5: Solve for x
   x = 1,150,061.42/1,211.67
6. Step 6: Final answer
   x = 949.15