Finding the Fourth Proportional to 1,389.38, 1,917.35 and 799.91

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.38 : 1,917.35 = 799.91 : x
2. Step 2: Convert to fraction form
   1,389.38/1,917.35 = 799.91/x
3. Step 3: Cross multiply
   1,389.38x = 1,917.35 × 799.91
4. Step 4: Simplify right side
   1,389.38x = 1,533,693.85
5. Step 5: Solve for x
   x = 1,533,693.85/1,389.38
6. Step 6: Final answer
   x = 1,103.87