Finding the Fourth Proportional to 1,389.38, 1,917.28 and 759.90

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.38 : 1,917.28 = 759.90 : x
2. Step 2: Convert to fraction form
   1,389.38/1,917.28 = 759.90/x
3. Step 3: Cross multiply
   1,389.38x = 1,917.28 × 759.90
4. Step 4: Simplify right side
   1,389.38x = 1,456,941.07
5. Step 5: Solve for x
   x = 1,456,941.07/1,389.38
6. Step 6: Final answer
   x = 1,048.63