Finding the Fourth Proportional to 1,389.56, 1,917.60 and 800.28

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.56 : 1,917.60 = 800.28 : x
2. Step 2: Convert to fraction form
   1,389.56/1,917.60 = 800.28/x
3. Step 3: Cross multiply
   1,389.56x = 1,917.60 × 800.28
4. Step 4: Simplify right side
   1,389.56x = 1,534,616.93
5. Step 5: Solve for x
   x = 1,534,616.93/1,389.56
6. Step 6: Final answer
   x = 1,104.39