Finding the Fourth Proportional to 1,389.79, 1,917.88 and 800.38

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.79 : 1,917.88 = 800.38 : x
2. Step 2: Convert to fraction form
   1,389.79/1,917.88 = 800.38/x
3. Step 3: Cross multiply
   1,389.79x = 1,917.88 × 800.38
4. Step 4: Simplify right side
   1,389.79x = 1,535,033.19
5. Step 5: Solve for x
   x = 1,535,033.19/1,389.79
6. Step 6: Final answer
   x = 1,104.51