Finding the Fourth Proportional to 1,399.40, 2,097.28 and 872.09

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.40 : 2,097.28 = 872.09 : x
2. Step 2: Convert to fraction form
   1,399.40/2,097.28 = 872.09/x
3. Step 3: Cross multiply
   1,399.40x = 2,097.28 × 872.09
4. Step 4: Simplify right side
   1,399.40x = 1,829,022.16
5. Step 5: Solve for x
   x = 1,829,022.16/1,399.40
6. Step 6: Final answer
   x = 1,307.00