Finding the Fourth Proportional to 1,398.50, 1,931.50 and 1,211.68

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.50 : 1,931.50 = 1,211.68 : x
2. Step 2: Convert to fraction form
   1,398.50/1,931.50 = 1,211.68/x
3. Step 3: Cross multiply
   1,398.50x = 1,931.50 × 1,211.68
4. Step 4: Simplify right side
   1,398.50x = 2,340,359.92
5. Step 5: Solve for x
   x = 2,340,359.92/1,398.50
6. Step 6: Final answer
   x = 1,673.48