Finding the Fourth Proportional to 1,389.63, 1,917.91 and 800.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.63 : 1,917.91 = 800.05 : x
2. Step 2: Convert to fraction form
   1,389.63/1,917.91 = 800.05/x
3. Step 3: Cross multiply
   1,389.63x = 1,917.91 × 800.05
4. Step 4: Simplify right side
   1,389.63x = 1,534,423.90
5. Step 5: Solve for x
   x = 1,534,423.90/1,389.63
6. Step 6: Final answer
   x = 1,104.20