Finding the Fourth Proportional to 1,389.34, 1,917.23 and 799.90

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.34 : 1,917.23 = 799.90 : x
2. Step 2: Convert to fraction form
   1,389.34/1,917.23 = 799.90/x
3. Step 3: Cross multiply
   1,389.34x = 1,917.23 × 799.90
4. Step 4: Simplify right side
   1,389.34x = 1,533,592.28
5. Step 5: Solve for x
   x = 1,533,592.28/1,389.34
6. Step 6: Final answer
   x = 1,103.83