Finding the Fourth Proportional to 1,389.78, 1,917.71 and 792.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.78 : 1,917.71 = 792.05 : x
2. Step 2: Convert to fraction form
   1,389.78/1,917.71 = 792.05/x
3. Step 3: Cross multiply
   1,389.78x = 1,917.71 × 792.05
4. Step 4: Simplify right side
   1,389.78x = 1,518,922.21
5. Step 5: Solve for x
   x = 1,518,922.21/1,389.78
6. Step 6: Final answer
   x = 1,092.92