Finding the Fourth Proportional to 1,399.28, 1,927.68 and 1,139

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.28 : 1,927.68 = 1,139 : x
2. Step 2: Convert to fraction form
   1,399.28/1,927.68 = 1,139/x
3. Step 3: Cross multiply
   1,399.28x = 1,927.68 × 1,139
4. Step 4: Simplify right side
   1,399.28x = 2,195,627.52
5. Step 5: Solve for x
   x = 2,195,627.52/1,399.28
6. Step 6: Final answer
   x = 1,569.11