Finding the Fourth Proportional to 1,311.78, 1,968.72 and 1,229.67

Step by Step Solution

1. Step 1: Write the proportion equation
   1,311.78 : 1,968.72 = 1,229.67 : x
2. Step 2: Convert to fraction form
   1,311.78/1,968.72 = 1,229.67/x
3. Step 3: Cross multiply
   1,311.78x = 1,968.72 × 1,229.67
4. Step 4: Simplify right side
   1,311.78x = 2,420,875.92
5. Step 5: Solve for x
   x = 2,420,875.92/1,311.78
6. Step 6: Final answer
   x = 1,845.49