Finding the Fourth Proportional to 1,434.40, 1,981.20 and 1,389.04

Step by Step Solution

1. Step 1: Write the proportion equation
   1,434.40 : 1,981.20 = 1,389.04 : x
2. Step 2: Convert to fraction form
   1,434.40/1,981.20 = 1,389.04/x
3. Step 3: Cross multiply
   1,434.40x = 1,981.20 × 1,389.04
4. Step 4: Simplify right side
   1,434.40x = 2,751,966.05
5. Step 5: Solve for x
   x = 2,751,966.05/1,434.40
6. Step 6: Final answer
   x = 1,918.55